The invention relates to the technical field of computer hardware modeling, and provides a GPU (Graphics Processing Unit) line rasterization boundary calculation optimization method, which comprises the following steps of: 1, selecting a starting point and an end point of a straight line, and selecting the starting point and the end point of the straight line; 2, calculating the height of each chip element, and calculating the height of each chip element according to a linear equation when a straight line is scanned; Step 3, calculating the height difference between each chip element and the starting point, keeping the height of the straight line starting point, and calculating the height difference between the current chip element and the starting point according to the height value obtained in the previous step; And 4, boundary comparison: comparing the height difference calculated in the step 3 with the overall height difference of the straight line: when the height difference is greater than the overall height difference of the straight line, modifying the height of the sheet element to be the final height, otherwise, keeping the height of the sheet element. The method solves the problem that the height threshold value substituted by error accumulation exceeds, especially the problem that the intersection points of adjacent lines are not uniform during continuous line drawing, and optimizes the GPU line rasterization algorithm.