用到STM32F405RGT6的板子，单独使用串口通信和CAN通信时都没问题，但结合在一起时串口只发送两个字符就停止了。
附上CAN通信和串口的配置信息，CAN通信只配置并未使用。
/////////////////////////////////////////CAN通信
#include"main.h"
void CAN2_Init(void)
{
        CAN_InitTypeDef        can;
    CAN_FilterInitTypeDef  can_filter;
    GPIO_InitTypeDef       gpio;
    NVIC_InitTypeDef       nvic;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);
        RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN1, ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_CAN2, ENABLE);

    GPIO_PinAFConfig(GPIOB, GPIO_PinSource12, GPIO_AF_CAN2);
    GPIO_PinAFConfig(GPIOB, GPIO_PinSource13, GPIO_AF_CAN2);

    gpio.GPIO_Pin = GPIO_Pin_12 | GPIO_Pin_13 ;
    gpio.GPIO_Mode = GPIO_Mode_AF;
    GPIO_Init(GPIOB, &gpio);

    nvic.NVIC_IRQChannel = CAN2_RX0_IRQn;
    nvic.NVIC_IRQChannelPreemptionPriority = 1;
    nvic.NVIC_IRQChannelSubPriority = 1;
    nvic.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&nvic);

    nvic.NVIC_IRQChannel = CAN2_TX_IRQn;
    nvic.NVIC_IRQChannelPreemptionPriority = 0;
    nvic.NVIC_IRQChannelSubPriority = 1;
    nvic.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&nvic);

    CAN_DeInit(CAN2);
    CAN_StructInit(&can);

    can.CAN_TTCM = DISABLE;
    can.CAN_ABOM = DISABLE;   
    can.CAN_AWUM = DISABLE;   
    can.CAN_NART = DISABLE;   
    can.CAN_RFLM = DISABLE;   
    can.CAN_TXFP = ENABLE;     
    can.CAN_Mode = CAN_Mode_Normal;
    can.CAN_SJW  = CAN_SJW_1tq;
    can.CAN_BS1 = CAN_BS1_9tq;
    can.CAN_BS2 = CAN_BS2_4tq;
    can.CAN_Prescaler = 3;   //CAN BaudRate 42/(1+9+4)/3=1Mbps
    CAN_Init(CAN2, &can);

    can_filter.CAN_FilterNumber=14;
    can_filter.CAN_FilterMode=CAN_FilterMode_IdMask;
    can_filter.CAN_FilterScale=CAN_FilterScale_32bit;
    can_filter.CAN_FilterIdHigh=0x0000;
    can_filter.CAN_FilterIdLow=0x0000;
    can_filter.CAN_FilterMaskIdHigh=0x0000;
    can_filter.CAN_FilterMaskIdLow=0x0000;
    can_filter.CAN_FilterFIFOAssignment=0;//the message which pass the filter save in fifo0
    can_filter.CAN_FilterActivation=ENABLE;
    CAN_FilterInit(&can_filter);

    CAN_ITConfig(CAN2,CAN_IT_FMP0,ENABLE);
    CAN_ITConfig(CAN2,CAN_IT_TME,ENABLE);
}


void CAN2_TX_IRQHandler(void) //CAN TX
{
  if (CAN_GetITStatus(CAN2,CAN_IT_TME)!= RESET)    //if transmit mailbox is empty
  {
           CAN_ClearITPendingBit(CAN2,CAN_IT_TME);   
  }
}

/////////////////////////////////////////////////////串口通信
void uart1_init(u32 bound){
   //GPIO¶Ë¿úéèÖÃ
        GPIO_InitTypeDef GPIO_InitStructure;
        USART_InitTypeDef USART_InitStructure;
        NVIC_InitTypeDef NVIC_InitStructure;
       
        RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB,ENABLE); //ê1ÄüGPIOAê±Öó
        RCC_APB2PeriphClockCmd(RCC_APB2Periph_USART1,ENABLE);//ê1ÄüUSART1ê±Öó

        //′®¿ú1¶Ôó|òy½Å¸′óÃó3éä
        GPIO_PinAFConfig(GPIOB,GPIO_PinSource7,GPIO_AF_USART1); //GPIOA9¸′óÃÎaUSART1
       
        //USART1¶Ë¿úÅäÖÃ
        GPIO_StructInit(&GPIO_InitStructure);
        GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7; //GPIOA9óëGPIOA10
        GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;//¸′óÃ1|Äü
        GPIO_InitStructure.GPIO_Speed = GPIO_Speed_2MHz;        //Ëù¶è50MHz
        GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP; //éÏà-
        GPIO_Init(GPIOB,&GPIO_InitStructure); //3õê¼»ˉPA9￡&#172A10

   //USART1 3õê¼»ˉéèÖÃ
        USART_StructInit(&USART_InitStructure);
        USART_InitStructure.USART_BaudRate = bound;//2¨ìØÂêéèÖÃ
        USART_InitStructure.USART_WordLength = USART_WordLength_8b;//×Ö3¤Îa8λêy¾Y¸ñê½
        USART_InitStructure.USART_StopBits = USART_StopBits_1;//ò»¸öí￡Ö1λ
        USART_InitStructure.USART_Parity = USART_Parity_Even;//ÎTÆæżD￡Ñéλ
        USART_InitStructure.USART_HardwareFlowControl = USART_HardwareFlowControl_None;//ÎTó2¼têy¾Yá÷¿ØÖÆ
        USART_InitStructure.USART_Mode = USART_Mode_Rx;        //êÕ·￠Ä￡ê½
    USART_Init(USART1, &USART_InitStructure); //3õê¼»ˉ′®¿ú1
       
    USART_Cmd(USART1, ENABLE);  //ê1Äü′®¿ú1
       
        USART_ClearFlag(USART1, USART_FLAG_TC);
       
//#if EN_USART1_RX       
        USART_ITConfig(USART1, USART_IT_RXNE, ENABLE);//¿aÆôÏà1ØÖD¶Ï

        //Usart1 NVIC ÅäÖÃ
  NVIC_InitStructure.NVIC_IRQChannel = USART1_IRQn;//′®¿ú1ÖD¶Ïí¨μà
        NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=3;//ÇàÕ¼óÅÏ輶3
        NVIC_InitStructure.NVIC_IRQChannelSubPriority =1;                //×óóÅÏ輶3
        NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;                        //IRQí¨μàê1Äü
        NVIC_Init(&NVIC_InitStructure);        //¸ù¾YÖ¸¶¨μÄ2Îêy3õê¼»ˉVIC¼Ä′æÆ÷¡￠

//#endif
       
}


void USART1_IRQHandler(void)                        //′®¿ú1ÖD¶Ï·tÎñ3ìDò
{
        u8 Res;
#if SYSTEM_SUPPORT_OS                 //èç1ûSYSTEM_SUPPORT_OSÎaÕæ￡¬ÔòDèòaÖ§3ÖOS.
        OSIntEnter();   
#endif
        if(USART_GetITStatus(USART1, USART_IT_RXNE) != RESET)  //½óêÕÖD¶Ï(½óêÕμ½μÄêy¾Y±ØDëêÇ0x0d 0x0a½áÎ2)
        {
                Res =USART_ReceiveData(USART1);//(USART1->DR);        //¶á衽óêÕμ½μÄêy¾Y
               
                if((USART_RX_STA&0x8000)==0)//½óêÕÎ′íê3é
                {
                        if(USART_RX_STA&0x4000)//½óêÕμ½áË0x0d
                        {
                                if(Res!=0x0a)USART_RX_STA=0;//½óêÕ′íÎó,ÖØD¿aê¼
                                else USART_RX_STA|=0x8000;        //½óêÕíê3éáË
                        }
                        else //»1ûêÕμ½0X0D
                        {       
                                if(Res==0x0d)USART_RX_STA|=0x4000;
                                else
                                {
                                        USART_RX_BUF[USART_RX_STA&0X3FFF]=Res ;
                                        USART_RX_STA++;
                                        if(USART_RX_STA>(USART_REC_LEN-1))USART_RX_STA=0;//½óêÕêy¾Y′íÎó,ÖØD¿aê¼½óêÕ          
                                }                 
                        }
                }                    
  }
#if SYSTEM_SUPPORT_OS         //èç1ûSYSTEM_SUPPORT_OSÎaÕæ￡¬ÔòDèòaÖ§3ÖOS.
        OSIntExit();                                                                                           
#endif
}



void Usart3_Init()
{
        USART_InitTypeDef usart3;
    GPIO_InitTypeDef  gpio;
    NVIC_InitTypeDef  nvic;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB,ENABLE);
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_USART3,ENABLE);

    GPIO_PinAFConfig(GPIOB,GPIO_PinSource10,GPIO_AF_USART3);
    GPIO_PinAFConfig(GPIOB,GPIO_PinSource11,GPIO_AF_USART3);

    gpio.GPIO_Pin = GPIO_Pin_10 | GPIO_Pin_11;
    gpio.GPIO_Mode = GPIO_Mode_AF;
    gpio.GPIO_OType = GPIO_OType_PP;
    gpio.GPIO_Speed = GPIO_Speed_100MHz;
    gpio.GPIO_PuPd = GPIO_PuPd_NOPULL;
    GPIO_Init(GPIOB,&gpio);

    usart3.USART_BaudRate = 115200;          // speed 10byte/ms
    usart3.USART_WordLength = USART_WordLength_8b;
    usart3.USART_StopBits = USART_StopBits_1;
    usart3.USART_Parity = USART_Parity_No;
    usart3.USART_Mode = USART_Mode_Tx|USART_Mode_Rx;
    usart3.USART_HardwareFlowControl = USART_HardwareFlowControl_None;
    USART_Init(USART3,&usart3);

    USART_ITConfig(USART3,USART_IT_RXNE,ENABLE);
    USART_Cmd(USART3,ENABLE);

    nvic.NVIC_IRQChannel = USART3_IRQn;
    nvic.NVIC_IRQChannelPreemptionPriority = 2;
    nvic.NVIC_IRQChannelSubPriority = 0;
    nvic.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&nvic);
}


感谢各路大神了！