Abstract: A fast line clipping algorithm against a convex polygonal window based on Skala algorithm is presented in this paper. By the algorithm, the clipping window is first divided into four polylines, then the clip of a line against the window is performed by determination of the intersection of the line with each of the four polylines according to the positional relationships between the two end points of each polyline and the line to be clipped. A bisearch method is used to quickly find out the window's edges that intersect the line to be clipped. The algorithm uses less multiplication and division operations and has higher execution speed, in comparison with the others like Cyrus-Beck algorithm and Skala algorithm.