Abstract: Accuracy of baseline vector is one of important factors that affect the accuracy of height inspaceborne InSAR.By calibrating the baseline vector can effectively improve target’s position accura-cy,now most baseline calibration methods adopt two-dimensional model.This model ignores along-track baseline,which decrease calibration accuracy.According to working theroy of spaceborne In-SAR,this paper presents a three-dimensional baseline model.By constructing the local moving coordi-nate system,the proposed method simplifies parameters and optimizes process in calibration.Resultsshow that the proposed method has practical value and can be used in the calibration of high accuracybaseline vector.