I found the answer myself.

      $(function(){
         $('#test').treegrid({
            title:'TreeGrid',
            iconCls:'icon-ok',
            width:700,
            height:250,
            rownumbers: true,
            animate:true,
            collapsible:true,
            fitColumns:true,
            url:'treegrid_data2.json',
            idField:'id',
            treeField:'name',
            showFooter:true,
            rowStyler:function(row){
               if (row.persons > 1){
                  return 'background:#AAD684;color:#fff';
               }
            },
            columns:[[
                   {title:'Task Name',field:'name',width:180},
               {field:'persons',title:'Persons',width:60,align:'right'},
               {field:'begin',title:'Begin Date',width:80},
               {field:'end',title:'End Date',width:80,rowspan:2},
               {field:'progress',title:'Progress',width:120,rowspan:2,
                   formatter:function(value){
                      if (value){
                         var s = '<div style="width:100%;background:#fff;border:1px solid #ccc">' +
                               '<div style="width:' + value + '%;background:red">' + value + '%' + '</div>'
                               '</div>';
                         return s;
                      } else {
                         return '';
                      }
                   }
               }
            ]]
         });
      });
we can customize the output html for fields.
And it shows progress bar by css.
It was very easy to show progress bar.
   

As seeing the treegrid demo(TreeGrid Footer Row), you can see the progress bar.
Do you know how to show it?

 

I need to load data for node in tree grid.
There are some similar functions such as 'reload' or 'loadData'.
I'm looking forward to using loadData.
But loadData allows me to load data for entire treegird, but not for special node.
Do you know how to load data for special node?
something like this:
$('#treegrid').treegrid('loadData', data, nodeId);
Hoping for your help.

Regards,