Abstract:Based on the data of daily mean minimum air temperature of year and in January ,April,July,October (standing for winter,spring,summer and autumn respectively)f rom 241 stations in 1951~2000,we divided the whole nation into eight regions,an d studied the characteristics of daily minimum air temperature in different regio ns and seasons.By the research we found that:under the background of the global climate warming,the increase of daily minimum air temperature is remarkble.Espec ially in the late part of the mid 1980s,the increase in the North of China is mo re conspic uous than in the South of China and the Qingzang plateau.During the 50 years,the first warming catastrophe of daily minimum air temperature takes place around t he mid 1970s.The warming trend in this time isn′t significant ,mainly in the fo rm of fluctuation.There is the second warming catastrophe after the mid 1980s,th e warming trend in this time is significant.By studying the data of different s easons,we still found that the dayily minimum air temperature has a trend of dec line in the South of China and the Qingzang plateau.