The invention relates to an airborne SAR image automatic target positioning method, which convert the coordinates of a target in the SAR image into an actual geographic coordinates of the target on the earth by utilizing the flight information (location, speed, etc.) of an aerial carrier and the SAR image information (resolution, center distance, central
Doppler frequency, etc.). Based on a range-Doppler equation, the invention combines an
earth model equation to carry out an target location, which not only can realize an absolute localization without a
control point, but also considers the influence of the
earth model on positioning accuracy; on the other hand, Taylor
series expansion is used for carrying out the
linearization of nonlinear equations; an
iterative method is adopted to solve the equation, thus improving the positioning speed; meanwhile, the initial value point of an iterative computation is appropriately selected according to the
operation mode of
radar, thereby controlling a converging direction in the iteration and avoiding a target
confusion. As a positioning method without the
control point, the automatic target positioning method of the invention has the advantages of high accuracy and high speed, thereby being capable of carrying out a real-
time processing and suitable to various airborne SAR systems.