By use of the monthly mean air temperature data at 160 stations in China during 1951-2000 and based on the analysis of seasonal and interannual variations,the interannual and interdecadal variations of the air temperatures in North China are emphatically studied in this paper.It is found that the air temperatures in winter in North China were lower in 1950-1960’s,began to rise in 1970’s,changed smoothly in 1980’s and got much warmer in 1990’s.The warming trend was obvious in the recent 50 years and reached to a rate of 0.27℃/10-year.The trend in North China was similar with those in the most areas of China,however,its warming rate was the highest among them.