Abstract: This paper presents a new fast algorithm for contour clipping against general complex polygon windows. Firstly， the new algorithm builds the bounding box of the clipping polygons and creates the constraint grid structure. And the algorithm uses the grid structure to pre-clip the contours quickly. Through linked structure to clip the contours， it can get the final clipping result. This paper can realize the method of row scanning to judge the inside and outside attribute by building the linked structure and reduce the counts of segments intersection. Through many experiments， the new algorithm is proved to be very effective and stable.

Key words: contours, bounding box, constraint grid structure, segments intersection