In order to improve the laboratory geometric calibration accuracy of directional polarimetric camera (DPC), the influence of collimator divergence angle on image point positioning accuracy is analyzed, the error model is established, and the image point positioning error is corrected by improving the target equation when fitting the geometric model parameters. The results of the comparative verification experiment show that the proposed method improves the calibration accuracy of the geometric calibration method based on collimator, and the improvement is more obvious when the field of view is larger. When the divergence angle of the collimator is 2° and the incident field of view is 50°, the calibration accuracy is improved by at least 0.15 pixel. The high-precision laboratory geometric calibration will provide accurate initial geometric parameters for the on-orbit geo-positioning and the registration of multi-angle, multi-spectral, polarization images of the DPC.