Abstract: Based on the observation data of Shiquanhe Earth-atmosphere Exchange Comprehensive Observation Station in Ali area in 2019 and the radiation observation data of the Shiquanhe Meteorological Station from 1993 to 2016, the diurnal cycle, diurnal variation, seasonal variation and interannual variation characteristics of total radiation and net radiation in Ali area are analyzed. The results show that: (1) The average daily variation peak of total radiation and net radiation in Ali area appeared at 14: 30 ~ 15: 00, the maximum monthly mean of total radiation appeared in June, and the maximum monthly mean of net radiation appeared in August. In the past 20 years, the average daily variation peak and monthly mean maximum of total radiation and net radiation in Ali area were delayed. (2) From 1993 to 2016, the exposed radiation of total radiation in Ali area showed a weak decreasing trend, but its daily maximum irradiance showed a very significant decreasing trend. The exposed radiation of net radiation showed a very significant increasing trend, but its daily maximum irradiance showed a weak decreasing trend. (3) From 1993 to 2016, the occurrence time of the daily maximum value of total radiation and net radiation in Ali area showed a very significant delay trend, and the occurrence time of the daily maximum value of average annual net radiation was about 13 minutes earlier than that of the daily maximum irradiance of total radiation.