The blasting spot monitoring is very important to reduce the occurrence of emergencies and to protect the workers' safety in practical applications. In this paper, we design an early warning system based on WSN (Wireless Sensor Network) which can be used in explosion operations. This system consists of two parts: the hardware part mainly uses several sensors to capture data we need and transmits them to the monitor center through wireless module; the software part mainly receives and processes the captured data, then analyzes the parameters to judge whether the environment parameters are abnormal, if yes, it will alarm in advance to protect the workers. Experiment results show that this system can alarm correctly when the environment parameters are out of limit, which improves the system's reliability and gets some social economic benefits in the meantime. This system does have a grand application prospect.