A millimeter-wave high-power handling capacity circularly polarized shared-aperture transceiver reflectarray antenna is proposed and designed. The short helical reflection antenna is proposed to be the reflectarray element. The 360° phase shift can be achieved by rotating the helical element. A flat-top shaped beam shared-aperture transceiver array antenna feed is designed to improve the efficiency and power capacity of the reflectarray antenna. The reflectarray with the aperture size of 49.5 × 49.5 mm2 is designed and simulated. The full-wave simulation results show that at center frequency of 30 GHz, the gain of the antenna is 22.5 dB with the efficiency of 57.8%, and the axis ratio is 0.8 dB. In the range of 26 to 34 GHz, the reflection coefficient is lower than -17.8 dB, with the relative bandwidth of 26.7%. The 1-dB gain bandwidth is 19.4%. Under air condition, the power capacity of the element antenna is 898 W, and the power capacity of the reflectarray antenna is 19.2 kW.