Abstract: In order to reduce the affect of the deformation offset of different installation platforms on the ground thermal drift calibration of multiple star sensors, a multiple star sensor ground thermal drift calibration position error detection method was proposed. Theoretical analysis and experimental verification were carried out. The position deviation data of the reference square prism deformation in the system under the vacuum of -25℃~60℃ was obtained. And the accuracy analysis of calibration position error was carried out.The results show that, the maximum offsets of the multi-star sensor positions around each axis are -39.341″/℃, -0.060″/℃, and -24.137″/℃, repectively. By establishing the error detection model which was established according to the method of measuring position error, the position error was removed from the offset of the attitude measurement result to obtain a more accurate star sensor attitude measurement quaternion. And the system accuracy after removing the position error was improved by at least 11%, which means it has a good application prospect in improving the accuracy of star sensor thermal drift calibration.