裁剪是计算机图形学中的一个基本问题，在绘制矩形网等值线的时候，会遇到某片状或环状区域没有采集数据点分布、地区边界区域、插值不准确的区域等涉及到剪切处理的情况，然而，目前国内外的一些著名剪切算法对于圆滑后的矩形网等值线的剪切处理，由于时间复杂度太高和区域的复杂性而显得力不从心，为了解决这一问题，提出了一种适合矩形网等值线图剪处理的算法，其概述为：（1）将单个剪切多边形内的等值点或者是嵌套环内的等值点置一为2.0；（2）记录多边每个边出发的等值线的追踪方向；（3）增加等值线追踪结束条件，用实际的大数据量进行了各种裁剪区域的测试，实践证明，这种方法对于矩形网等值线的复杂区域剪切处理快速有效。

clipping is one of basic problems in computer graphics.Some condtions relating to clipping will be met when people draw grid contour,such as some sheet or ringy region without date point, region's boundary,some region with inaccurate interpolation point. However, at present,some famous clipping algorithms home and aboard are almost impossible to process grid contour's clipping after it is smoothed because time complexity is too high and region is too complicated.In this paper, an algorithm suit for the clipping of grid contour to solve the problem is presented. The algorithm may be summed up the following three steps:①filling the clipping region with -2.0 by calculating the point of intersection between contour and clipping region and sorting the point of intersection and partnering the point of intersection.②recording the direction of trace of contour from every boundary of clipping region.③increaseing the end condition of contour that begin from some boundary of clipping region and to own boundary or other clipping region' s boundary.As a result,the algorithm passed the test of practical large data.The examples shown in the paper and other applied examples demonstrated that the method of clipping is fast and effective for complex region of grid contour.