A system model for the simulation of stereo mapping camera is presented. The system is divided into some parts: atmospheric radiation transmission, satellite platform, optical system, camera radiation response and so on. The numerical simulation technology can be used to complete end-to-end analysis and assess the feasibility of physical imaging system design, and predict the stereo mapping camera on-orbit imaging capability. In this paper, we take visible imaging stereo system as example. The high precision and high resolution surface physical model is used as the input source. First of all, the interior and exterior camera elements are used to calculate the observation vector on the all pixels of CCD photosensitive surface in forward-looking and faced-looking camera. And then according to the imaging camera parameters for ground targets, the radial brightness of the camera into the pupil is calculated. Finally, through the ray tracing algorithm and point spread function of optical system model, the probe on the surface of the target radial flux is calculated. Then the digital image is obtained by probe radiation response model. The experimental results show that the geodetic precision of physical model for faced-looking camera is 124 m, and that for forward-looking camera is 193 m, indicating that more reliable simulating stereo images can be obtained by this simulation method.