In this paper, the warmth index (WI) and coldness index (CI) in Inner Mongolia from 1961 to 2016 were analyzed,and the spatiotemporal distribution of these indexes and their changes before and after the temperature mutation were concluded. The results showed that the tendency rates of WI and CI were distributed in an inlaid pattern before the temperature mutation; after the temperature mutation, the tendency rate of WI was mainly in an increase trend,but that of CI was mainly in a decrease trend. In the context of climate warming, the CI in Inner Mongolia was holistically decreased after the temperature mutation,which revealed that it also became colder in cold season in east Inner Mongolia under the climate warming,and there were the sharp changes of both warmth and coldness. The five-year a moving average results showed that the heat increase in warm season was relatively stable, but the heat increase or decrease in cold season fluctuated obviously. The CI was in a decrease trend since the 21st century,and such decrease occurred 10 years earlier than that of WI. The tendency of CI in east Inner Mongolia was significantly decreased after the temperature mutation,and the tendency rates of WI and CI were distributed in an inlaid pattern in the central and western parts of Inner Mongolia.