1，我们需要做的是画线。2，循环调用画线实现动画效果。3，将像素设置高调节毛边。

完整代码：

var zhima_score = getParameterByName('zhima_score');        var setIter;        var canvas = document.getElementById('canvas'),            ctx = canvas.getContext('2d'),            n = 40,            rad = Math.PI * 2 / 100;        canvas.width = 800;        canvas.height = 800;        $(function () {            if (zhima_score && parseInt(zhima_score) > 0) {                $('.tip2').text(zhima_score);                writeCircle();            } else {                $('.tip2').hide();                $('.tip1').hide();                $('.tip3').show();                $('.sure').text('离开');            }            ctx.strokeStyle = "#F0F4F4";            ctx.lineWidth = '40';            ctx.beginPath();            ctx.arc(400, 632, 360, 40 * rad, 110 * rad, false);            ctx.stroke();            $('.sure').click(function () {                identificationFinish();                myObj.identificationFinish();            })        })        function go() {            if (n < 98) {                var grd = ctx.createLinearGradient(0, 180, 160, 160);                grd.addColorStop(0, '#21C8B3');                grd.addColorStop(1, '#204E92');                ctx.strokeStyle = grd;                ctx.lineWidth = '40';                ctx.beginPath();                ctx.arc(400, 632, 360, 40 * rad, n * rad, false);                ctx.stroke();                n += 3;            }        }        function writeCircle() {            setIter = setInterval('go()', 80);        }