Aiming at the death of detained children in school bus, a detection and alarm system based on ZigBee technology is developed. The system detects the children′s detention through the sound sensor and infrared sensor in ZigBee wireless sensor network, and uploads the data to the control center to judge if there is any abnormality. If there is an abnormality, the control alarm system gives the sound and light alarm prompt, and sends the alarm short message to the designated number through GSM module. The design gives full play to the four advantages of ZigBee wireless sensor network: low power consumption, low cost, distributed and self-organizing. The function of the system is realized by software and hardware design. The experimental results show that the system has high success rate and short response time in detecting abnormal situations. It can play an escort role for the safety of children′s lives.