Although the multilevel fast multipole algorithm (MLFMA) has been the most popular method in electromagnetic field computation, the limitation of both CPU speed and memory size make it still difficult to solve the scattering problems from very large scale structures using this method. In this paper, we implemented the CFIE (combined filed integral equation) into our parallel MLFMA solving the electromagnetic scattering problem of an electrical-large PEC targets on the message passing interface (MPI) in a cluster system. A lot of numerical results are represented in this paper. From the numerical result presented a very good convergence speed is achieved, and the scattering from a very large scale problem which has about 1 million unknowns is solved. Finally, the result is presented and discussed in this paper.