Abstract: By analysis of 8 meteorological stations in Tongliao for 53 years （1961-2013） the beginning,the final frost date and frostless period sequence,their variation trends and climatic characteristics of sudden change were explored, it pointed out that first frost early with the tendency 2.3d/10a, the final frost delayed with the tendency 2.1d/lOa, the frostless period prolonged with tendency 4.4d/10a.