Abstract: After analysis of causes of the warpage distortion of parts in rapid prototyping,a novel tool-path planning,parallel raster scanning and filling path planning,is presented.By this approach,a two-dimensional plane region can be filled or scanned in an approximately parallel manner.The temperature grads in XY directions can be reduced while the constraint force originating from cooling shrinkage in different area can be homogenized.Consequently,the quantity of distortion can be decreased.Experimental results show that the algorithm calculates the tool-paths with more ascendant performance than other approaches.