A space debris impact risk assessment model was developed on the basis of the existing space debris environment model. The framework of the model consists of space debris environment module, spacecraft model module, geometry shading module and impact probability module. The impact risk by space debris for three generic spacecraft geometries were offered by IADC in order to validate different models. The result was proved to be effective by comparing with other models. The space debris impact risk for the spacecraft of cube was assessed and analyzed using the developed risk assessment model, and the effect of orbital altitude, inclination and attitude parameters to the space debris impact risk was presented.