Abstract: Based on the daily mean temperature data from 29 meteorological stations from 1961 to 2014 and RegCM4 (Regional Climate Model 4) model data from 2010 to 2059 in the Changbai Mountains,annual heating degree days were calculated,its spatio-temporal variation characteristics were analyzed,and the relationships between heating degree days and annual mean temperatures were investigated.The results show that the value of annual heating degree days in the Changbai Mountains is high and fluctuates in a range of 4311.8-5723.7℃·d.The value of annual heating degree days is higher in the northern part and lower in the southern part of the Changbai Mountains.The value of annual heating degree days tends to decrease since 1961,especially since 1989 to 2009.From 2010,it tends to increase slightly again.There is a clear negative relationship between the value of heating degree days and annual mean temperature.Under RCP (Representative Concentration Pathway) 4.5 and RCP 8.5 scenarios,it is expected that heating degree days would decrease with increasing in temperature from 2010 to 2059.