The stored grain can be regarded as a complex ecosystem, which exist a complex multi-field coupling interaction among the abiotic factors, the biotic factors, and the surrounding environment. In this system, only a few parameters such as temperature can be accurately detected, which causes the system to operate like a “black box” to the outside world. To truly and accurately detect various grain pile parameters, and further study the multi-field coupling interaction in grain piles, a graphical detection system for multi-filed interaction in grain storage based on NMR has been developed. The system consists of an NMR imaging analyzer, a test grain bin, and a data acquisition and processing system, which can accurately detect the grain pile temperature, humidity, and moisture simultaneously, and intuitively and vividly present the cloud map of the temperature field, humidity field, and moisture field in the grain pile through the cloud map drawing software. In this system, the NMR imaging technology was applied to the research field of multi-field coupling interaction in grain piles for the first time, which can provide a new technical means to find out the complex coupling relationship of stored grain ecosystem and further confirm the correctness of relevant theoretical research. The development of this system will be helpful in deepening the theory of multi-field coupling and biological field of grain piles, developed by the industry.