The digital post-processing is needed to restore the image of high quality from the blurring image output directly from optical sparse aperture imaging systems. The common method for post-processing is the Wiener filter,where the important parameter is the point spread function (PSF) which should be known. The Wiener filter will deconvolve the convolution effect if the PSF is the precise impulse response of the optical sparse aperture system. Usually it is hard to measure the PSF experimentally. On the contrary,it is easy to calculate the PSF based on designed array configuration of the optical sparse aperture system. In order to evaluate whether the calculated PSF is adaptable to the image restoration,a theoretical analysis of the image restoration has been done by using these two kinds of PSFs. The results show that the calculated PSF works well in the case that the co-phasing error is small,while the measured PSF is ineffective.