Abstract: In order to indirectly measure the flux density distribution of the solar tower concentrator by concentrating the moonlight,a solar dish concentrator as an optical stable point-focusing system should be used to investigate the effect of moon shapes on concentration ratio distribution（CRD）. This paper presents a new simulation model for the moonlight CRD of the dish concentrator. In this simulation model,a blocking non-circular moon-shape model for the changing moon has been established using photographed moon images. The laser-scanned point cloud data of mirrors is analyzed for the accurate mirror surface. The reflected points are sampled uniformly on the mirror surface. The tracking error of the concentrator is also considered in this simulation model. The mirror error model and the moon shape model are combined into the equivalent moon shape. The simulated CRD images have good cosine similarities to the experimental moonlight images,the cosine similarity α is always above 95%.