Aiming at the problem that the drought situation in the source area of the Yellow River is increasing year by year, the statistical downscaling results of eight models under two emission scenarios(RCP4. 5 and RCP8. 5)of CMIP5 model are used, and the multi-mode ensemble optimization technology of optimal weighting is used to construct the precipitation and temperature data sets of two emission scenarios(RCP4. 5 and RCP8. 5). On this basis, the VIC(variable information capacity)model of the source area of the Yellow River is constructed. Combining with PDSI(Palmer drought severity index), the temporal-spatial characteristics and change trend of the drought in the source area of the Yellow River are analyzed. The results show that the PDSI of the research area in the reference period(1961—1990)is relatively stable, showing a slight increase trend, while in the future period(2021—2050), PDSI is significantly increased. From 1961 to 1990, the frequency of drought in most areas of the Yellow River source area was about 10 times, the average duration of drought was 4~10 months, and the average intensity was 6~24. In the future, the average duration and intensity of drought in the two scenarios are less than those in the reference period, and the variation amplitude in the RCP8. 5 scenario is significantly higher than that in the RCP4. 5 scenario.