Abstract Temperature alarm monitoring system is composed of Intel 8 single chip microprocessor AT89S51 as the controller, using DS18B20 digital temperature sensor with 9 effective ways to read the temperature, is transmitted to the microprocessor temperature processing analysis. Then the SCM software through the analysis and calculation of the temperature value after through one of a total of four digital tube display. At the same time, workers can use general keys on temperature alarm system control, convenient for the upper and lower limits of the value change of temperature alarm. When the temperature exceeds the warning value, the buzzer will produce corresponding sound. At the same time the three-color LED time temperature range display. The system can accurately measure the temperature of 0.5 degrees Celsius,1 degrees Celsius above shows the temperature difference. At the same time, when the temperature exceeds the threshold, CPU through the relay is connected to an external device, convenient temperature regulation.