Abstract: In order to improve the accuracy of measurement result of optical lenses with large depth of field in industrial visual inspection, image restoration must be carried out on the intermediate image in order to obtain a more accurate measurement result, and the point spread function (PSF) is the key to the image restoration. Non-diffracting imaging system was designed according to the formula of maximum non-diffracting distance of axicon, based on the scalar diffraction theory, PSF of the system was theoretically deduced by the stationary phase method within frequency range. Using the theory of quasi monochromatic light, the relationship between the PSF and the axicon angle or defocus was analyzed under incoherent light illumination. Simulations and experimental results show that the intensity of central spot of PSF is stronger and the density of diffraction fringes is larger when the refracting angle increases, while the influence of defocus on PSF has an opposite effect.