1.先建CSS .required {  
    background-image:url(../pic/bitian.gif) !important;  
    background-repeat:no-repeat;  
    background-position:left;
    padding-left:12px; 
                          
}   2.在创建的field里加入CSS     xtype: 'textfield',
  value: '50,000',
  anchor: '100%',
  cls:'required',
   fieldLabel: ' {MOD}结算'