Abstract: Regional drought acts as one of the major meteorological disasters in agricultural production,and drought index plays a fundamental role in drought monitoring and early warning. Taking Zhangye City as the research area,this paper analyzes the applicability of SPEI and scPDSI index.With a comparative analysis of two indices with relative humidity,runoff,normalized vegetation index（NDVI）and actual drought records,it shows that there is high consistency between scPDSI and drought history events and scPDSI has the most significant correlation with relative humidity,runoff and NDVI index. It indicates that scPDSI has good applicability in Zhangye. Based on scPDSI exponential change sequence,the characteristics of drought evolution in Zhangye from 1935 to 2017 are analyzed by M-K mutation test and wavelet periodic analysis. It is found that the study area shows a tendency to become wet after the 1980 s,there are many dry and wet mutation points,with alternate cycles of drought and flood,and there are three distinct cycles of 24 a,14 a and 6 a. At the same time,changes of dry and wet cycle in Zhangye area may be related to solar activity and El Ni?o-Southern Oscillation（ENSO）activity. The research findings serve as a reference for the application of scPDSI in similar arid areas.