Tasks such as global mapping and overseas target positioning have the higher and higher requirements for space remote sensing geometric calibration and positioning accuracy. The current measurement error of the image pixel coordinates does not match the accuracy of the ground control points (GCP), which limits the reliability of the calibration results of the space sensors. The point source target has a good geometry in the aerospace image and can provide precise pixel coordinates for the geometric calibration task. In this paper, the pixel coordinates of the simulated point source images are solved, and the errors the pixel coordinates are below 0.04 pixel and the root mean square error is only 0.01 pixel, superior to those by the current measurement software and the manual selection. In addition, the effect of pixel measurement error on the calibration and positioning results is examined. The results show that the use of point source target as GCP can make the calibration parameter and positioning accuracy better than those using the traditional GCPs. In the absence of GCPs, adding two point source targets can reduce the positioning error to the decimeter level. The point source target can effectively improve the accuracy of geometric calibration and positioning results and has the potential to develop into a new generation of geometric calibration tools.