This paper addresses the research of fidelity and flexibility of remote sensing image generation modeling and simulation, and presented a synthetic image generation model which deals spectrally with multifold effects base on a three dimension digtial geometric scene and raytracing render engine. At first this paper tried to set up the imaging simulation system from the completeness and expansibility angle by stratifing and modularizing each important factor of whole imaging chain. In order to effectively utilize existing calculation model and able to interoperate for the new algorithm model, the call and communication relations between each module is designed by combining existing 3d technology, light tracing technology, sensor simulation technology. And the radiance calculation module, the ray tracing calculation module and sensor effect simulation module were discussed. Then aimed at a space scene simulation application. The model framework, submodels and spectral image examples achieved by C++ programming language are presented which can be widely use in sensor prototyping, algorithm testing , efficiency assessment at satellite design phase.