AT89S52 microcontroller was the center controler for wireless temperature measurement and alarm system, through temperature measurement circuit and remote wireless alarm circuit, realized the temperature detection and off-limit alarm of the ambient temperature. The system was composed of temperature acquisition circuit, display circuit and alarm circuit. Temperature sensor was DS18B20, real-time temperature displayed via LED displayer. Users can customize the alarm lower limit and superior limit. when the ambient temperature exceeds the alarm limit, the microcontroller will start the sound and light alarm, and remote wireless alarm. Temperature measurement range from -40 °C to +85 °C, measurement accuracy is 0.5 °C, wireless alarm distance is up to 100 meters. This system is of high precision, wide temperature measurement, and timely alarm.