Abstract: To solve the problem of high precision calibration of three-dimensional baseline of space-borne distributed interferometric synthetic aperture radar(InSAR), a new method of baseline calibration is proposed. Firstly, this method combines the slave radar Doppler equation and the slave radar distance modification equation to form the baseline calibration model. Based on the ground control points, the least square iteration is used to solve the baseline three axial errors. Compared with the baseline calibration model based on the slave radar distance modification equation, the baseline calibration model optimizes the coefficient matrix condition number of the normal equation, reduces the morbidity of the matrix, and improves the calibration precision. Then, according to the baseline calibration, the baseline vector is actually used to intersect by the ground control points, and the intersection angle can be increased to improve the accuracy of the intersection. The control point layout strategy is given, that is, the control points are laid separately at the near and far ends of the radar footprint at ground. Compared with the way of laying control point uniformly, we can significantly improve the calibration precision and robustness. Finally, the spaceborne distributed InSAR simulation data was used to carry out the baseline calibration experiments based on different control points number, different control points precision, and different control points layout. The experiments show that the new method can achieve high-precision result of three-dimensional baseline calibration, namely, millimeter-scale in cross-track, along-track and radial baseline direction respectively, which can provide a new way for the baseline calibration of spaceborne distributed InSAR.