In order to satisfy the requirement of broadband communication in C-band, a broadband high gain circularly polarized microstrip antenna with gap coupling laminated structure was designed. The radiation patch with double layered chamfering was used to achieve circular polarization and expand the bandwidth of antenna. The feeder was deviated from the center of the dielectric plate, and the axial ratio characteristic of the antenna was improved. The metal reflector was used to realize the directional radiation of the antenna, and the gain was increased. The measurement results showed that 10 dB impedance bandwidth of the proposed antenna reached 32.2%(from 4. 17 to 5.76 GHz) and the 3 dB axial ratio (AR) bandwidth reached 20.2% (from 4. 25 to 5. 25 GHz), and the gain of the antenna was greater than 8.5 dB in the axial ratio bandwidth range. With the characteristics of wide bandwidth and high gain, the antenna was suitable for C band broadband communication.