Based on finite difference time domain (FDTD) method, the numerical simulation of filtering characteristics of the two dimensional metal grid which include the well-shaped grid, the array of complementary square metallic pill and the cross wire-hole array are carried out. The results show that the well-shaped metal grid structure achieves a high-pass of filter function, the array of square metallic pill achieves a low-pass of filter function, and the cross wire-hole array structure achieves a band-pass of filter function. Simulation results show that, with the increasing of the period the cut-off frequency of high-pass filter and low-pass filter move to low-frequency, and the center frequency allowed by the cross wire-hole array similarly moves to the low-frequency. The result of the multi-layer structure of the cross wire-hole array shows that, the rising edge and the falling edge become very steep when the spacing between layers is 20 μm and the more than 5 layers are used which greatly improved the filtering performance.