An intelligent constant temperature control and display circuit is realized by using 89C2051 single chip microcomputer and DS18B20 digital temperature sensor. The software design of constant temperature controller is based on OrCAD/Capture. The hardware include the 89C2051, LED display circuit and power supply module. In the low temperature environment, the controller can start the electric heater, controlling the temperature in the range of 28 to 34 degrees Celsius, and displays the result on the front panel in real time.