Abstract: By analyzing the monthly sunshine duration of Kulun in Tongliao Inner Mongolia during 1961 and 2014, we compared with their variation characteristic and analyzed the historical evolution of sunshine duration and the interannual and inter-season and inter-monthly variation characteristics using simply mean value, monadic linear regression and Mann-Kendall methods. The results showed that the sunshine duration showed a trend of decrease and the climate tendency rate was-46.525h/10 a. The performance of seasonal change of sunshine duration in winter presented the increasing trend slowly but the decreasing trend in spring, summer, autumn. The rainy season had a greater impact on sunshine duration.