We proposed a novel high precision spaceborne InSAR baseline estimation approach based on interferometric fringe frequency which makes the improvements from two aspects:the baseline calculation formula and the fringe frequency estimation precision.The accurate mathematic relationship between the baseline parameters and the interferometric fringe frequency was deduced considering the earth curvature.Also the Semi-Newton iterative method was introduced to estimate the fringe frequency of each pixel in the complex interferogram.Furthermore

the frequency evaluation was processed by the linear fitting to suppress the noise and the high precision fringe frequency was obtained.With the accurate frequency and the deduced baseline calculation formula

the baseline estimation precision was improved to centimeter.Finally

the computer simulation was employed to confirm the new baseline estimation approach.