To solve the problem that it is difficult to give early fire-warning for forest, the feasibility of using a single element mercury cadmium telluride (MCT) infrared detector in the field of forest fire prevention is analyzed. By utilizing the characteristics of high sensitivity, low power consumption and low cost of single element MCT infrared detectors, an omnidirectional scanning forest fire early warning system based on a single element MCT detector is designed. The system is powered by solar energy and wind energy. Its infrared detector is used to implement the collection, amplification, processing and imaging of the mid-infrared radiation signals of forest fire. The collected signals are sent to the computer monitoring center through RS485 and GPRS. When a fire occurs, the system can send the fire early warning information to firefighters stably in time under various geographic and climate conditions.