just add

var pid = "{$vo['bm_scheme_cid']['pid']}";  //23  
var phtml = '<option value=""></option>';
$.each(citylist,function(i,v){
     phtml += '<option value="'+v['id']==pid?'selected':''+'">'+v['name']+'</option>';
});
$("select[name='backmoney_basetpl_pid']").html(phtml);

just to be on the safe side

var pid = "{$vo['bm_scheme_cid']['pid']}";  //23  
var phtml = '<option value=""></option>';
$.each(citylist,function(i,v){
  if (v['id']===pid) {
    phtml += '<option value="'+v['id']+'" selected >'+v['name']+'</option>';
  } else {
    phtml += '<option value="'+v['id']+'">'+v['name']+'</option>';
  }
     
});
$("select[name='backmoney_basetpl_pid']").html(phtml);