By employing grid data and observed records, the temperature and precipitation trends and their significances on runoff of rivers originated in most regions of Gansu Province were discussed. Trend analyses show that from 1961 to 2011, most of the study area experienced significant (p<0. 05) increases in temperature, while there were opposing trends for precipitation in regions to the east and west of Wushaoling Mountain. Temperature and precipitation trends played different roles on the runoff among each subregions. Over the past five decades, due to the significant increases of precipitation, the Heihe River and Shulehe River originated in the west of Wushaoling Mountain has experienced significant increase in runoff; while due to the significant decrease in precipitation and temperature rise occurred in their drainage basins, the other rivers suffered from decreased runoff. In the whole regions, correlation analyses show that the runoff of rivers is more closely related with precipitation(R=0. 735, p<0. 0005) than that of temperature (R =0. 541, p<0. 0005). At a large time scale, owing to the enhancements of evaporation motivated by temperature rise, there is an obvious decreasing trend in runoff of rivers originated in Gansu Province.