tooltip : {
        trigger: 'axis',
        formatter:function(params)
        {
           var relVal = params[0].name;
           for (var i = 0, l = params.length; i < l; i++) {
                relVal += '<br/>' + params[i].seriesName + ' : ' + params[i].value+"%";
            }
           return relVal;
        }
    },
 

參考文件：

http://echarts.baidu.com/doc/doc.html#Tooltip

http://echarts.baidu.com/doc/example/tooltip.html#