Abstract: Based on the data of first frost date, latest frost date and frost-free period in Ewenki Autonomous Banner Inner Mongolia collected from 1961 to 2010, the variations of first frost date, latest frost date and frost-free period in this region were statistically characterized. The results showed that the average date of first frost was September 11 th, the average date of latest frost was May 6th, and the average frost-free period lasted for 128 days.