The entire image chains simulation for the optical remote sensing images system is still at the starting stage in China. By analyzing the interactions between the atmosphere, the scene and remote sensor, imaging process is divided into three parts: the construction and organization of 3D scene, the simulation of the at-sensor radiance images and simulation of the sensor effects. The functions of each module and conceptual data flow among these modules are analyzed briefly. At last, the effects of terrain fluctuations and the view zenith angle on imaging are discussed. The results show that with the increase in pixels height from 0 to 1 km, the relative errors of the radiance at-sensor can reach 170%. And the maximum relative error of the radiance at-sensor is close to 50% with the change of the view zenith angles from 180° to 124.4°.