In this letter, an ultrathin reflective polarization converter with the total thickness of 1/62 wavelengths is proposed to realize the high efficiency of cross-polarization conversion at 32 GHz. Two metasurfaces overlapped on the same layer with a displacement are designed to improve its polarization conversion performance, angular stability, and conformal adaptability. Due to the flexibility of the polyimide substrate, a planar and a conformal converter are conveniently fabricated by the printed circuit board technology. Experimental results show that the maximum conversion efficiency of the planar converter is higher than 94.3%, which is rather close to the simulation prediction. Meanwhile, a cross-polarization conversion efficiency of 88.1% can be obtained by the conformal converter with a 100 mm curvature radius, which demonstrates the validity of the overlapped array design. Due to the ultrathin thickness and flexibility, the proposed converter has great application potential in polarization control devices, on-chip antennas, and wearable antennas.