The internal temperature of the grain piles is an important indicator of moldy decay of the grain. Real-time monitoring of changes in the internal temperature of the grain piles is an important task in preventing grain mildew. In order to solve the problems of large-scale monitoring of outdoor bulk grain piles and difficulty in cable deployment, a wireless remote temperature monitoring system for bulk grain was designed. The field data collection station was powered by batteries, and a low-power working mode was designed and optimized. The system is of no wiring, low power consumption and easy maintenance, etc., The wireless communication between the host monitoring system and the terminal adopts a simplified Modbus command, which further reduces the wireless communication power consumption of the terminal. This system has achieved good results in practical applications.