Due to the high frequent drowning accident, a new type of drowning-preventing device established on the base ofBeiDou Navigation Satellite System, using the compatibility of GPS tech, GSM, GPRS and other Internet of Things technology as well as Vital Signs Detection technology is designed. The situation whether a person is in drowning is judged by the device monitoring the heart rate and oxygen saturation. And the device utilizes Global Positioning System module to find exact location and uses GPRS to send the information of life signal and position. Based on the experiment, this system can decrease the rate of the drowning accident tosome extent.