In recent years, with the popularization of swimming, the danger of drowning in the process of swimming is increasing day by day. If the drowning person cannot be found in time, the swimmer will face great danger or even lose his life. Aiming at the existing problems of swimming pool, monitoring equipment and rescue system, an active calling device for swimming pool based on wireless communication technology is designed. The whole device is composed of two parts: transmitter and receiver. The information is transmitted by wireless data transmission module between them. The water level electrode sensor is used to detect the state of the swimmer in the water, to confirm whether the swimmer is drowning, and to alarm in time. The device is scientific in design and easy to use. Through the active call for help, the rescue efficiency of the swimming pool is improved to a certain extent, and the risk of safety problems for swimmers is reduced.