According to the working principle and the actual correction of the RFID microstrip antenna, this paper designed a new type of rectangular microstrip antenna which worked under the condition of circular polarization, and in this design, the new type of rectangular microstrip antenna is obtained by loading an equal number of rectangular slot in the each broadside of the symmetrical triangle cutting angle antenna. On the basis of triangular symmetrical corner cutting antenna, and by using the Ansoft company's HFSS10.0 software, we modeled and optimized the parameters of the new type of microstrip antenna. The results show that the new microstrip antenna has better reflection coefficient compared with the triangular symmetrical angle cut antenna. And at the same time, the new type of microstrip antenna has better antenna gain and bandwidth.