Abstract: Due to the limitations of a single drought index in evaluating drought,a new comprehensive drought index(PCA_prs)is constructed to provide theoretical support for drought monitoring and defense in the Qinhe River Basin. Based on the hydrological and meteorological elements of the Qinhe River Basin simulated by the SWAT model,this paper calculates three drought indices in the Qinhe River Basin:Standardized Precipitation Evapotranspiration Index（SPEI）,Standardized Runoff Index（SRI）,Standardized Soil Moisture Index（SSI）. The combination of three drought indexes through Principal Component Analysis（PCA）methods constructs the Qinhe River Basin’s short-term,medium-term and long-term PCA_prs;the results show that:（1） The constructed PCA_prsreflects the drought monitoring results that are consistent with actual drought events. Compared with a single drought index,PCA_prsintegrates precipitation,evapotranspiration,soil moisture and runoff and other factors,the description of the drought in the Qinhe River Basin is more realistic;the evaluation of the drought in the Qin River Basin is more comprehensive；（2）PCA_prsof different time scales is more targeted for identifying drought events of different duration；（3） The short-term PCA_prsand the mid-term PCA_prscan be used to monitor the real-time changes of drought in the study area;and the long-term PCA_prsis more suitable for describing the long-term drought development trend. It shows that PCA_prscan be used for drought monitoring in the Qinhe River Basin,and provides a new reference for drought resistance research in this region.