To solve the problem that the traditional leaky wave antenna can only radiate linearly polarized waves, a new type of circularly polarized leaky wave antenna is proposed. The plasma waveguide is composed of uniform metal strips. The corrugated circular patches are loaded on either side of the Spoof Surface Plasmons （SSP） waveguide periodically and asymmetrically, and the scanning angle of the antenna beam can be effectively broadened. Besides, circular polarization performance is obtained by introducing perturbation on the radiating elements. The simulated results show that the antenna exhibits an impedance bandwidth of 43.5% (<-10 dB) and a 3 dB axial-ratio bandwidth of 31.3%. The impedance bandwidth of the beam steers is varied from 120 to 70 ° as frequency varies from 4.5 to 7.0 GHz. The antenna maximum gain is 12.48 dB in the whole band. Featured with a simple structure, easy fabrication and stable performance, the leaky wave antenna can be applied in wireless communication and sensor systems.