Abstract: A planetary wheel running mechanism was designed to adapt to the store environment of complex terrain and changeable geology of the cobalt and hydrothermal sulfide investigation area in the deep-sea bed. A dynamic model of obstacles for the planetary wheel running mechanism was established based on the virtual work principle. The structural characteristics of the planetary wheel running mechanism were derived by analyzing obstacle height effect factors with a transmission ratio of 1:2.25. The obstacle (the altitude of 900 mm) process for both sides of a planetary gear train was analyzed in ADAMAS. It is proved that the physical dimension of the planetary gear train, bodywork center position and attachment coefficient are the key effect factors. The driven moment, velocity and normal pressure sharply increased as each wheel surmounting obstacles, but they were moderate after the front wheel came over the obstacles. Another weaker pulse occurred when the rear wheel began climbing, and then the parameters reached a plateau. This mechanism transforms between an ordinary gear train and a planetary gear train, and it has good autonomous obstacle performance.