In recent years, with the rapid development of network communication, 5G technology has brought about higher network speed and more communication requirements. Internet of Things technology has been widely used in many fields. Therefore, this paper realizes the physical health monitoring system under the Internet of Things and 5G communication technology to detect the physical health of teenagers in real time. Based on the in-depth analysis of the theoretical research and application status of the healthy Internet of Things at home and abroad, this paper first studies the theories and methods of teenagers’ physical health information collection, collects human body temperature and movement steps, respectively, through wearable devices based on RFID anticollision algorithm, and further estimates human health and movement. The prototype system of the adolescent physical health monitoring system is realized. The system is divided into the terminal node and client information management system: (1) The terminal node is divided into information collection node and information collection node. The hardware circuit of the collection node mainly includes a microcontroller module, a sensor module, and a power circuit, and the collection node mainly includes a microcontroller module, a serial port module, and a power circuit. (2) The client information management system is divided into PC end and the mobile end. The PC end uses asp.net and SQL Server technology to design the database and user interface, and the mobile end uses WeChat public platform for development and design.