In view of the low level of intelligence in monitoring and controlling the granary environment by manual and semi-automatic methods in the process of grain storage in China, an intelligent granary monitoring system based on OneNET cloud platform is designed for real-time remote monitoring and intelligent control of granary. The system takes STM32 chip as the intelligent node, and monitors the temperature and humidity, light intensity, CO2 and other environments of the granary in real time. After the collected information is fused by weighted average method, it intelligently controls the opening and closing of insulation doors and windows. Through the wireless WiFi module ESP8266, the collected granary data is transmitted to OneNET cloud platform in real time, so that the granary administrator can remotely monitor the granary. The system improves the intelligent level of granary environmental information monitoring, ensures the quality of granary storage, and has certain popularization and application prospects.