By embedding the PIN diodes in the metasurface and delicately designing the feed circuit, a cross-shaped switchable polarization conversion metasurface is proposed. When the diodes are in the on state, the metasurface works in the polarization conversion mode, the PCR exceeds 90% in the range of 4.037.71 GHz, and the corresponding relative bandwidth is 62.7%. However, when the diodes are in the off state, the polarization conversion is turned off, and the metasurface works as a reflector. The mechanism of the polarization conversion metasurface is explained by theoretical analysis and surface current distributions. The designed metasurface has good wide-angle incident characteristics, and the metasurface has good polarization performance within the incident angle of less than 45°. Furthermore, the measured and simulation results agree excellently, which confirms the feasibility of this work. The proposed metasurface is expected to be used in EM compatibility and polarization detection.