A temperature real-time monitoring system was devised based on MATLAB GUI. It improved the data processing speed and software development efficiency. Serial port tool box in MATLAB and Modbus communication protocol were used to link up thermostat to PC. Variety operating modes can be achieved in different parameter configurations. The software source file is 304 KB. Test results show that, the temperature response curves of different parameters configuration are quite accurate. The sampling interval was 1s and the measurement accuracy was 0.1°C.