Abstract: A radially polarized optical parametric amplifier insensitive to polarization is provided by the present invention, which comprises a laser module and a nonlinear crystal satisfying the type-II phase matching or the type-II quasi-phase matching condition, wherein the laser module is configured to generate two laser beams, namely the pump light and the signal light with an arbitrary polarization state, the wavelengths of the pump light and the signal light are degenerate or nearly degenerate; and the nonlinear crystal is provided in the emergent beamline of the laser module to perform optical parametric amplification of the signal light by using the pump light.