Temperature difference and dew point are two important factors for moisture condensation of the storage grain. According to the large temperature humidity, storage temperature and humidity, grain temperature conditions and rice moisture during the discharge period of the finished grain rice, the reasons for moisture condensation were concluded. Using the relevant charts such as grain pile dew point approximation checklist, grain absolute humidity graph and atmospheric absolute humidity map, the main method of grain pile dew predicting were summarized and the feasible and effective treatment measures were provided which has positive significance for the safe storage of finished grain.