A novel dual frequency microstrip antenna with low Radar Cross Section (RCS) is proposed in this paper. Compared with the traditional microstrip antenna, the novel microstrip antenna loaded Complementary Split-Ring Resonators (CSRRs) has a low RCS. The novel and traditional dual-frequency microstrip antennas with the center frequency of 3.4GHz and 5GHz are designed and fabricated. The results demonstrate that the monostatic RCS of the proposed antenna has been well reduced. The RCS reduction at 5GHz is as much as 17dB.