The Internet of Things (IoT) is developing at an explosive speed, and its impact on the world is becoming increasingly prominent. As a key trend in modern home life, smart home has become one of the core application scenarios of IoT technology, and the practical application of relevant technologies in the smart home field has achieved initial results. With the continuous maturity of the application of IoT technology in smart home systems, aiming at the potential security risks existing in current smart home systems (such as the demand for real-time monitoring of residential environments) and the limitations of existing home security systems, this paper designs a highly networked smart home security system based on IoT. The system takes the detection, interception and alarm of unauthorized access as its core objectives, and its hardware architecture includes two nodes with CC2530 chip as the main control: one is the coordinator node, which is responsible for network establishment, maintenance and data interaction with the PC terminal; the other is the terminal device node, which undertakes the task of controlling various functional modules and transmits the collected data to the coordinator. The functional modules equipped in the system mainly include a temperature and humidity collection module, a smoke detection module, a relay module and a human body infrared sensor module. This paper conducts research on the IoT-based home security system, not only analyzing its working principles from the theoretical perspective, but also building a simple home environment security monitoring system from the hardware perspective.