Abstract: In order to reveal the change rule of the main extreme temperature index and the reason of its formation in Hebei Province in the past 34 years and improve the prediction of extreme temperature events in the region,to provide scientific basis for the prevention and control of agricultural meteorological disasters in the whole region,by using daily average temperature,daily maximum temperature,daily minimum temperature observation data of 21 stations in Hebei Province during 1980—2013,extreme cold (warm) index characteristics of temporal and spatial variation has been studied,as well as the reasons of its characteristic difference.The results show that the extreme warm index shows an increasing trend,and the extreme cold index shows a decreasing trend.The number of blazing days increases slowest,while the number of frost days increases fastest,and the number of freezing days drops slowest,the number of frost days reduces fastest.The linear trend of the number of hot days and the number of stuffy days in the 3 extreme warm index is positive,and the former is gradually increasing from the northeast to the southwest,while the latter is the opposite.The linear trend of extreme high temperature events is positive and negative,and the linear trend in the northeast to the southwest gradually reduces,except for coastal areas.The linear trends of the 4 extreme cold index are positive and negative,negative region are bigger than the positive region.The linear trend of freezing days in addition to the Qinhuangdao area from northeast to southwest in addition,and linear trends of frost days,low temperature days and extreme low temperature event days change in a complex way.Extreme cold (warm) index has been much affected by regional climate change,especially in recent years on the regional climate heating stagnation phenomenon in response.Altitude is an important cause for the extreme cold (warm) exponential days and linear trend,humidity is also one of the factors,but the impact is much smaller than the altitude.