A novel actuator controller for greenhouse control system is proposed in this paper. This controller can solve the problems existing in traditional greenhouse control system such as generating electric arc, short circuit risk, lack of communication and smart ability. We adopt five separate magnetic latching relays to control the three-phase motor. In order to prevent generating electric arc in the process of turning off relay, the alternating current zero-crossing detection circuit is designed. In software side, the relay-off task program is running in the real-time operating system, which can ensure turn-off operation at the point of alternating current zero-crossing. In addition, the controller is capable of detecting motors operation parameter and having multiple communication interfaces. Finally, we implement our controller in practice and experimental results meet the design requirements.