To determine the baseline of distributed SAR satellite formation at high accuracy, a CDGPS relative position method of distributed SAR satellite formation based on dynamic orbit model is presented. At first, CDGPS principle is introduced. And then, intersatellite relative position method based on dynamic orbit model is introduced. Based on CDGPS measurement, this method introduces prior restricted information provided by dynamic orbit model, and overcomes the disadvantage that kinematic single point position determination can not be used when observation geometry is bad or observations are not enough. This method can restrain the random errors in measurement, improve relative position accuracy and provide a technology approach to realize intersatellite baseline determination at mm level. At last, simulation computation verifies the efficiency of the dynamic method. Computational results show that the dynamic method can improve the relative position accuracy remarkably. Compared with kinematic method, the fixed solution accuracy of L1
is improved by 68%, and the fixed solution accuracy of ionosphere free combination is improved by 95%.