Abstract: Solar system small body exploration involves ground-/space-based long-distance observation, proximity observation, landing, sample return, etc. The topography characteristics of asteroid surface are studied and a simulation model to describe asteroid surface terrains with various sizes of boulder following the Power Law distributionis proposed in this paper. Five terrains cases are selected and simulated according to the requirement of proximity operation method/actuator verifications under the specific topographic structure limitations. Results show that simulated terrains havegood agreement with asteroid terrains images, by which the proximity operation verifications, such as landing mechanism and terrain relative navigation algorithms, could be done in preliminary.