Abstract: Based on meteorological data such as the maximum temperature, the minimum temperature and average temperature as well as data of corn yield and area in Horqin District of Tongliao City of Inner Mongolia during 1980-2009, the effects of chilling damage on corm in different developmental stages were comprehensively analyzed from the aspects of heat index, relationship between heat index and yield of maize, chilling damage index, changing trends of heat and chilling damage, temporal and spatial distribution of heat index and chilling damage frequency. The results can provide scientific basis for the growth stage of maize.