Abstract: Based on the data of average air temperature in winter and every month in November, December, January and February at 100 meteorological stations in Inner Mongolia during the period of 1961-2010, the equiprobability grade method was employed to discriminate the thresholds of cold/warm events at these stations, and the events were divided into strong and weak cases. The definition methods and grading standards of cold/warm events at these stations in west, east and whole Inner Mongolia were determined in terms of the relative proportion method. The results of the variation of winter cold/warm events were described. The response of general circulation anomalies to winter cold/warm events was investigated. The results showed that only the strong cold events occurred during the period of 1961-1987, but many strong warm events occurred during the period of 1988-2010. The strong cold events occurred occasionally since 2000. During the strong cold events, the enhanced Asia Polar Vortex moved remarkably southward due to the anomaly of northward movement of Urals and Okhotsk blocking highs in midupper troposphere, and the Siberia high on the ground was much stronger than the normal cases. During the strong warm events, the weaken Asia Polar Vortex moved remarkably northwestward. The Siberia high on the ground and the Urals and Okhotsk blocking highs in midupper troposphere were much weaker than the normal cases..