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Among the many environmental factors that affect cultural relics protection, humidity is the most important factor, and there are different humidity requirements for different materials. In order to preserve the artifacts in the museum, a small, accurate and stable humidity control system based on the fuzzy PID algorithm is designed and implemented. The system is divided into the host computer monitoring, humidity control equipment, field instrumentation and control algorithm four parts. The host computer uses the common PC, and uses C # to monitor the software programming; humidity control equipment uses the ARM Cortex ™-M3 kernel STM32F103ZET6 and its expansion module with the man-machine interaction module to carry on the operation; Field instrument mainly by the DS18B20 temperature sensor, SHT15 digital temperature and humidity sensors, fans, TEC cooling film composition. The temperature and humidity decoupling algorithm and the fuzzy PID self — tuning humidity control algorithm based on fuzzy control and PID control are designed. On the basis of the PID control, by calculating an error E and error change rate EC of the current system, the fuzzy inference using the fuzzy rules, fuzzy matrix table query self-tuning PID parameters to achieve precise control system. The results show that the system reduces the overshoot by 4.55% compared with the conventional PID control, and reduces the system adjustment time by 40.5%, which greatly improves the control effect.