The present invention provides a ground-contour-following autonomous obstacle avoidance mower for hillside orchards and a control method thereof. Through cooperation of a push rod motor and a rotating pair, multi-angle cutting is achieved, and energy consumption needed by mowing operation is reduced. A connecting rod is arranged and forms a flexible mechanism together with an upper base bearing, a lower base bearing and a base-connecting unthreaded shaft. The flexible mechanism interacts with the push rod motor to achieve ground contour following operation, so that the mower as a whole can conduct ground-contour-following mowing operation on a complex orchard terrain, with a better cutting effect than that of a traditional mower. The use of a right-angle bypassing obstacle avoidance mode realizes precise obstacle avoidance of the mower, and achieves the operation purpose of not excessively relying on operators.