Abstract: In the process of radar detection, there often exits some unwanted area information, such as highway, islands, high peaks and obscurants, and so on. Here, with the help of computer graphics calculation method, based on Bresenham straight line plotting algorithm to fit the radar beam, the relative position relationship between blanking area and the radar is calculated before the beam is swept, and the echo signals within the corresponding distance range are filter out, so as to achieve the purpose of area blanking. At the same time, a multi-threaded precomputation method is designed and planned for the pre-calculation of the detection area, to solve the timeliness problem in the real-time calculation process of the moving platform. Comparing experiments with typical algorithm, the blanking area identification results of the algorithm proposed in this paper fit the boundary more stably, and the computational efficiency has been greatly improved; the multi-threaded precomputation method can further improve the computational efficiency, which is applicable to the moving platform scenario.