A photovoltaic-module cleaning robot, an obstacle-surmounting method and device thereof are provided according to the present application. If the photovoltaic-module cleaning robot gets stuck during obstacle-surmounting, a lower end motor of the photovoltaic-module cleaning robot is controlled to operate reversely, so that the lower driving wheels thereof rotate reversely; an upper end motor of thereof is controlled to stop operating, so that the upper driving wheels thereof have no drive; and then, the photovoltaic-module cleaning robot is gradually restored to a horizontal state, and if it is determined that the photovoltaic-module cleaning robot meets a forward moving condition, the upper end motor and the lower end motor of the photovoltaic-module cleaning robot are controlled to simultaneously rotate forward to realize moving forward, thereby solving the problem of easily getting stuck at a drop height between adjacent modules.