The influences of CCD pixel size, random noise and quantization series on contrasts of the interferogram after sampling and the moiré fringes are analyzed based on digital moiré phase-shifting interferometry. The effects of interference fringe′s spatial frequency on the phase measurement accuracy are analyzed and simulated in detail. The results indicate that with the increase of interference fringe′s spatial frequency, the contrast and the signal to noise ratio of moiré fringes will be worse with the influences of the process of CCD sampling, random noise and quantization series. Furthermore, the phase errors will be greater after phase-unwrapping. When the interference fringe′s spatial frequency is lower than 0.45 λ/pixel, the phase measurement accuracy can be better than π/50, which is equivalent to the optical path difference better than λ/100. This provides a theoretical quantitative basis for the further study of extending the measurement range of digital moiré phase-shifting interferometry.