Abstract: Based on the time-domain physical optics (TDPO) algorithm, the method for the analytic scattering field of the triangular surface element is given in this paper. The expression for the calculation of the scattering field is obtained by the double integral of the triangular surface element. Compared with the traditional TDPO method, this method has a higher accuracy. In dealing with the problem of high frequency and complex target, this method requires less triangle surface elements, and can save computation time and computer memory.