Thanks for your reply but this code is for dependend pick list using passing parameter in api.  I need to do is using J query how to implement and by default value  will be all category list in picklist.

<apex:page controller="categories" readOnly="true">

     
    <apex:form id="FormB">
    <script>
       function myJavaMethod(){
          myactionfun();
      }
      </script>
      
	  <script>
       function myJavaMethod1(){
          myactionfun1();
      }
      </script>
	  
<!-- <apex:actionFunction name="myactionfun"  action="{!getperformcalloutpageReference}" reRender="testPanel"/>-->
	 
<!--  <apex:actionFunction name="myactionfun1"  action="{!getcompanypageReference }" reRender="testPanel1"/>-->
	  
	
     <apex:outputPanel id="testPanel12">
	<apex:pageBlock >
             <apex:pageblockSection columns="3" >
                  <apex:pageBlock >
                 <apex:selectList size="1" value="{!PartnerId}" id="PartnerId" onchange="myJavaMethod1(); return false;"> 
                <apex:selectOptions value="{!company}" /> 
                   <apex:actionSupport event="onchange" >
                    </apex:actionSupport> 
                </apex:selectList>
                </apex:pageBlock>
     </apex:outputPanel>       
         
        
    
    
    
  <apex:outputPanel id="testPanel1">
         <apex:pageBlock >
             
                 <apex:selectList size="1" value="{!ContentCategoryId}" id="ContentCategoryId" onchange="myJavaMethod(); return false;" >   
                <apex:selectOptions value="{!items}" /> 
                <apex:actionSupport event="onchange">
                </apex:actionSupport>  
                 
                </apex:selectList>
               </apex:pageBlock> 
               
         </apex:outputPanel> 
          <apex:outputPanel id="testPanel">
         <apex:pageblock id="pgBlock2"> 
          <!--  <c:PageBlockTableEnhancerADV targetPbTableIds="a"  pageSizeOptions="5,10,15,30,40,50,60,70" defaultPageSize="50" enableExport="false"/> -->
            <apex:pageBlockTable id="a" value="{!performcallout}" var="wrap" width="100%"  rendered="{!normalList}">
            <apex:column headerValue="Title" value="{!wrap.Title}"/>
            <apex:column >
            <apex:inputCheckbox value="{!wrap.selected}" > 
            </apex:inputCheckbox>
            </apex:column>
            </apex:pageBlockTable> 
        </apex:pageBlock> 
        </apex:outputPanel>   
         </apex:pageBlockSection>
         </apex:pageBlock>
    </apex:form>
</apex:page>