Triangular rasterization is an indispensable part of the graphics processor. In order to improve the efficiency of triangle rasterization and reduce the hardware design cost of GPU. This paper combines the characteristics of Bresenham algorithm and adder-based divider to propose an improved Bresenham algorithm. And the algorithm is applied to triangle rasterization. The algorithm is verified by software simulation, and tested in the hardware test platform of FPGA. The results show that the improved Bresenham algorithm can achieve triangle rasterization better and consumes less hardware resources than the traditional Bresenham algorithm, which reduces the unit cost of GPU hardware design and improves the efficiency of triangle rasterization in GPU.