A new polarization diversity converter (PDC) is presented in this paper based on a multilayer frequency selective surface (MFSS). The MFSS consists of three-layer square patches with truncated corners and two-layer grid lines. The converter is considered as a free-rotating screen. The polarization of the transmitted wave can be reconfigured to linear polarization or circular polarization by rotating the different angles of PDC. The simulated fractional bandwidth of the 3dB axial ratio reaches 15% with respect to 10GHz frequency band. The measured results show the good performance of PDC, which is important for communication and remote sensing applications.