Abstract: In order to reduce the measurement errors of space attitude measuring instruments such as the star trackers, and improve the centroid accuracy of star point, a calibration method based on the phase-shifting interferometry principle was proposed, by studying the influence of the image detector's pixels geometric offset on the centroid accuracy of star point. The simulation model of image detector based on the properties of pixel response nonuniformity with pixels geometric offset was built, and the star centroid calculation was carried out in simulation. The simulation results proved that the pixels geometric offset of the image detector would produce parts of systematic errors to the centroid accuracy of star point. The image-detector pixel calibration results showed that under the condition of adding pixels geometric offset with the RMS value of 0.03 pixels and the 5% Gaussian white noise in the amplitude ratio, the calibration accuracy of the image detector pixel calibration method was better than 3×10^-4 pixel(1σ). The research results turned to be a feasible scheme for the calibration technology of the pixels geometric offset of image detector, and had great significance to improve the measuring accuracy of attitude measuring instruments such as the star trackers.