A reflection metasurface, composed of metallic annular rings, is presented for realizing high-efficient and polarization-independent focusing. By varying the inner and outer radii of the isotropic rings, we can achieve a full modulation on the phase from -180°to 180°. By properly arranging the annular rings, we design gradient metasurfaces for focusing without polarization sensitivity by finite element method simulations and further demonstrate the focusing effect with high-efficient and polarization-independent performance experimentally in the microwave domain. In addition, the structure is also proved applicable in the optical domain by simulations. This work expands the capabilities of metasurfaces to focusing and imaging applications without polarization limitations.