The quality of the reference wave front in point-diffraction interferometer (PDI) is constrained by the quality of the pinhole, and the deviation between an actual pinhole and a perfect one is caused by machining errors and the misalignment. The quality of the far-field wave front diffracted by a rough-edge circular pinhole and an elliptical pinhole is analyzed in detail based on Rayleigh-Sommerfeld diffraction formula. Pinhole edge roughness mainly causes the trefoil aberration in diffracted wave front, and the ellipticity of a pinhole will lead to a small amount of astigmatism in diffracted wave front. For pinholes with diameters from 0.4 to 1.0 μm, when the radius root mean square (RMS) deviations are 0, 15 and 30 nm, the RMS deviations of the diffracted wave fronts are in the order of 10-8λ, 10-4λ and 10-3λ, respectively. The results show that pinhole edge roughness has a significant influence on wave front deviation, while it has little to do with the intensity distribution in the diffracted wave front. The ellipticity of the pinhole has very small effect on wave front deviation, but affects the wave front intensity distribution in far-field wave front. Usually, the ellipticity of an elliptical pinhole resulting from machining errors or the misalignment is small, and its effect on far-field wave front quality can be neglected.