With continuous development of radar technology, radar polarization characteristics have been more and more widely applied in target feature extraction and recognition in recent years, especially, continuous development of high resolution imaging and complete polarization makes them become one of developing tendencies for modern radar. Warhead target in ballistic missile midcourse under the system of step frequency broadband radar, as an example, has been researched in this paper. Then, a method of obtaining complete polarization data of targets based on FEKO and generating complete polarization HRRP of targets has been proposed. Results show that this method is simple, highly efficient and substantial. The realization of complete polarization HRRP is achieved successfully.