Visible climate change in the interior catchment of arid northwest China during the past 40 years occurred. By analyzing the climate change in the Heihe River and the Taolaihe River catchments of the Qilian Mountains. the characteristics of climate change, the relation between climatic elements and annual streamflow in the catchments were discussed in this paper. Changes in alpine precipitation and temperature were seasonally different in the past 40 years. Precipitation in summer and winter appeared to i...