The invention provides a child safety watch used for realizing the wireless connection and information transmission with a vehicle-borne information system and an APP client. The invention also provides an application method for preventing a child from being trapped in a car based on the child safety watch, the connection with the vehicle-borne information system is established after a child wearing the watch enters the car, if the vehicle-borne information system judges that the child is trapped in the car through a sensing device in the car, the vehicle-borne information system sends information to the child safety watch, and the child safety watch sends alarm information to the APP client. According to the child safety watch, a connection is established between the vehicle-borne information system and the APP client in a wireless communication mode and information transmission is carried out, which is convenient and fast, the interactive functionality is strong, the reliability is high, the activities of the child in the car can be monitored according to needs, the risk that the child is trapped in the car is reduced, the alarm information is emitted when the child is trapped in the car, and the health and life safety of the child is ensured.