本文介绍了一种利用ARM、改进的buck 变换器和数字温度传感器DS18B20，采用模糊PID 控制算法构成的恒温控制器。该控制器所控温度与环境温差最大可达30°C，所控温度精度达±0.5°C。关键词：恒温控制；buck 变换器；模糊PIDAbstract:This paper discusses a constant temperature controller which uses ARM、modified buck converter、numeric temperatrure sensor DS18B20 and fuzzy PID control arithmetic.The maximum difference temperature of the controller and the environment temperature is 30 degree centigrade,the temperature precision which it controlls is ±0.5 degree centigrade.Keywords: constant temperature control;buck converter;fuzzy PID