Abstract: The baseline deviation introduces significant errors in the process of converting the relative angle measurement results to the main star coordinates.To solve this problem，the conversion deviation introduced by the baseline deviation in the range of azimuth and elevation angles（-60°，+60°）was studied，and a search algorithm for on-orbit calibration of the measurement baseline was proposed.This method used the close-range high-precision perception system carried by the satellite，and at the same time performed perception measurement of the slave star’s position，took the close-range perception system as the calibration data source，then searched for the baseline deviation and calibrated through the step acceleration algorithm，so that the perception results of the system were synchronized with the calibration data source，so as to achieve the purpose of measuring baseline calibration.After the search algorithm，the conversion deviation of azimuth angle and elevation angle is better than 001°，the maximum is 0.012°，which is lower than the maximum measurement error caused by thermal noise.

Key words: inter-satellite measurements, baseline deviation, relative angle measurement, conversion error, step acceleration method