Abstract: By analyzing the data of sunshine,clouds,fog,dust,and smoke and so on in Datong in last 45 years,the climate tendency was calculated using the least square method.The results showed that the average sunshine hours of Datong reduced 46.83 hours per 10 years,the percentage of sunshine,the total amount of low clouds,fog,sandstorm and dust tended to decrease,but the change of smoke days tended to increase,especially in winter.The increase was obvious in the mid of 1980s.This indicated that the sunshine decreasing in Datong was mainly due to the human activities,especially the increase of smoke and dust aerosols caused by the rapid growth of industrial emissions of pollutants.

Key words: Sunshine hours, Number of smoke days, Aerosol, Datong city