Bistatic forward-looking SAR image positioning error acquiring method

The invention discloses a bistatic forward-looking SAR image positioning error acquiring method. The method comprises a step 1 of establishing a rectangular coordinate system in same-direction-flying-mode forward-looking bistatic SAR module according to a platform and target speed relation and a platform and target position relations of a bistatic SAR, and acquiring the position coordinates and speed vectors of a receiving platform and an emitting platform at an initial zero time; a step 2 of acquiring platform position coordinates and speed vectors with errors when a platform position error and a speed error of the emitting platform and the receiving platform are given; and a step 3 of establishing a Doppler equation set according to a range-Doppler principle, and then acquiring the real position of each target point by using a Newton iteration method so as to obtain the positioning error of a target. The method does not use approximate operation and achieves accurate positioning error results. The method may effectively analyze an influence, caused by the kinematic error of the emitting platform of the bistatic SAR, on the image positioning error and an influence, caused by the kinematic error of the receiving platform of the bistatic SAR, on the image positioning error.