The invention provides a citrus picking robot system and a control method thereof. The picking robot system comprises a picking robot and a control system. The picking robot comprises a crawler type movable platform, a shell, a mechanical arm mounting platform, a mechanical arm, a binocular head, a monocular head and a picking mechanism. The control system comprises a central processing unit, an image processing module, a movable platform control module, a mechanical arm driving control module and a picking mechanism driving control module, and the image processing module, the movable platform control module, the mechanical arm driving control module and the picking mechanism driving control module are in control connection with the central processing unit. The picking path is planned by the central processing unit in advance, picking is precisely controlled through an inverse kinematics algorithm, the picking precision is high, and the picking efficiency is high. The picking robot executes picking according to the preset path and is good in navigation performance, and the problem of time consumption during picking can be solved. Whether the picking task is completed or not is circularly judged at each picking point, and therefore the problem that fruits are missed when picked can be solved, and manual secondary picking is not needed.