A passive target localization algorithm based on airborne imaging system is proposed. The precise calculation of target location can be achieved by using airborne imaging devices. Firstly, according to the lens design parameters, the target coordinate information in the image can be mapped to the location under ideal camera model. The target space coordinate information in the camera coordinate system can be calculated by using the image view and image resolution. Secondly, the target space location information in the inertia navigation coordinate system can be calculated by using the imaging system installation location and airborne posture information. Finally, according to the latitude, the longitude and the altitude of the airborne location, the target actual location can be calculated. The experimental results demonstrate that our proposed algorithm can achieve accurate target localization in less time.