Errors causesd by radial phase-shifting nonuniformity of test optics are different when using different steps of phase-shifting algorithms to process interference fringes. Here, a error analysis model is established based on optical principle of point diffraction interferometery. Take 5, 6, 7 and 13 step phase-shifting algorithms as example, phase-shifting errors which are directly caused by radial phase-shifting nonuniformity are first analyzed, and then be introduced into the interferometry model. The influence of this phase-shifting error to final optical surface testing results are analyzed later and a new polynomial error correction method based on error preestimate is proposed. The analysis results show that the more the phase-shifting steps are, the larger the figure error caused by radial phase-shifting nonuniformity is. Each of these figure error shows a paraboloid like distribution. Also, removing the defocus item from Zernike polynomial of final optical surface testing results is equal to have had a quadratic polynomial correction of this error. If the numerical aperture of test optics are no more than 0.3, the error caused by radial phase-shifting nonuniformity can be ignored after the quadratic polynomial correction.