Abstract: The hardware and software design method of a new type of constant temperature and constant humidity box's monitoring and controlling system was introduced in this paper. In order to achieve the constant temperature and constant humidity effect, the air compressor of the device used now must run at full speed and full power and then reach the temperature's balance by adjusting the heating apparatus. The energy consumption of above method is high and it is difficult to get a sound control. To solve this problem, the air compressor of the equipment adopts frequency modulation technique so as to turn the PID adjustment of refrigeration into reality. This method uses the SCM interface circuit's sharing technology which makes the whole hardware system simpler and more reliable. By using X25045 CMOS chip, this system has the function of automatic orientation and calibration.