Abstract: In this paper, a low profile high gain circularly polarized antenna based on aperture coupled metasurface is proposed. The antenna consists of a metasurface and a microstrip slot antenna, which are clinging to each other. Circular polarization waves can be generated by changing the size of the metasurface cut angle, while improving the antenna gain and widening the impedance bandwidth. In order to verify the simulation results, a sample antenna with a size of 1λ×1λ×0.067λ (at 10 GHz) was fabricated and measured. The simulation and measurement results show good consistency. The results show that the gain of the antenna is above 7.5 dB and the maximum gain is 10.5 dB over the entire working bandwidth, which is 5.3 dB higher than the ordinary slot antenna, the −10 dB impedance bandwidth and 3 dB axial ratio bandwidth can reach 27.4% and 12.3%, respectively. Therefore, the antenna can meet the requirements of low profile, circular polarization and high gain, and can be used in many fields.