Abstract: Positioning method aims to get the geographical coordinates of each pixel in SAR images. It is necessary to calibrate the parameters of the positioning model to increase precision. This paper presents a method based on sensitivity equations to calibrate the positioning model by linearizing the position errors. Then a method of joint calibration of the positioning model over large areas including several scenes is proposed, and it can achieve the positioning of large areas with few Ground Control Points (GCPs) by using Corresponding Points (CPs) between adjoining scenes. The results show that with few GCPs the accuracy of this method is better than polynomial ortho-rectification model and range-Doppler model.