Abstract: The planar elements method has been applied to calculating the echo characteristics of moving target such as the complex Benchmark submarine model in torpedo guidance trajectory. This method is verified by the Rayleigh normal mode solution of rigid sphere. Thus, the method can be used for calculating echo characteristics under the con-ditions as torpedo stern chasing method, torpedo advance angle fixing method and torpedo parallel approaching me-thod. The results provide an important theoretical basis for the echo characteristics study of underwater moving target.