The Mann-Kendall(M-K) statistical test method was used to analyze the rainfall data of Xiaojiang River basin in the upper reach of Yangtze River from 1950 s to 1990s in this article.The result of M-K test with 95% confidence interval shows that the annual rainfall amount has a notably increasing trend in 1990 s in the Xiaojiang River basin.The tendency of the increase sediment delivered by debris flows at Jiangjia ravine located in Xiaojiang River basin has close relation with the increase of the annual rainfall in 1990 s.The average annual sediment yield by debris flows in 1990 s is about 0.91 million more than that between 1965 and 1989.