Abstract: A parallelized finite-difference time-domain(FDTD) method for simulating the bounded wave electromagnetic pulse (EMP) simulator with lumped terminator and parallel plate is presented. The effects of several model-parameters on the simulator to the fields in the working volume are simulated and analyzed. The results show that if the width of the lower PEC plate is(or is bigger than)1.5 times that of the upper plate of working volume, the projection length of front transitional section does not have a significant effect on the rise-times of electric fields at the points near the front transitional section, and the rise-times of electric fields at the points near the working volume center decrease as the projection length increases, but the decreasement of rise-time decreases. The rise-times of Ez at all points also decrease as the lower PEC plates width increases, but the decreasement of rise-time decreases. If the projection length of the front transitional section is fixed, the good results can not be obtained by increasing or decreasing the height of the simulator only, however, which has an optimal value.