Based on the daily frost data of 46 meteorological observation stations in Jilin Province from 1961 to 2015,the climatic change characteristics of the first frost day,the last frost day and the frost-free period in Jilin Province were analyzed by means of M-K mutation analysis and climatic tendency rate. The results showed that the average first frost day was September 25, the last frost day was May 8, and the frost-free period was 139 days. The average first frost day of the province and each region showed a trend of postponing,the average last frost day showed a trend of advancing,and the average frost-free period showed a trend of prolonging,which almost passed the significance test of 0.01 level. Among them,the first frost day is the earliest in the east,the last in the west,the last frost day is the last in the east and the earliest in the west, which leads to the gradual increase of frost-free period from southeast to northwest. The average first frost day and the last frost day occurred abruptly in 1973 and 1993 respectively. More than half of the stations in Jilin Province passed the 0.05 level significance test in the trend of delaying the first frost day, advancing the last frost day and prolonging the frost free period.