In this paper, the calculation method of electromagnetic scattering is analyzed using method of moment in MPI (Message-Passing Interface) parallel environment. Due to the characteristics of Gauss elimination method, the approach of the matrix filling and solving by looping over column is described, which can save data communicating time between processors. The vehicle's scattered fields is calculated by the method using different numbers of processors. The results show that parallel computation can reduce computing time and memory requirements of each processor to the original's 1/process_num (processors number).