This Aiming at the problem that the radar cross section (RCS) of the traditional slot antenna array is too large, a new type of antenna is proposed that uses the polarization conversion metasurface (PCM) to reduce the radar cross section (RCS) and maintain the radiation characteristics of the slot antenna array. The wideband RCS reduction of the antenna is achieved without compromising the antenna performance. The PCM is placed on the upper surface of the slot array antenna and functions as an RCS reduction. The performance of slot antenna array loaded with PCM is analyzed. The impedance bandwidth of the antenna is 9.06-10.72 GHz, and the relative bandwidth is 16.6%. Under the impact of the normal direction plane wave in the wide frequency range of 8~12GHz, the single-station RCS is reduced by more than 8dB, and the maximum reduction amount reaches 21.5dB, achieving good radiation performance and scattering performance.