Abstract: Drought is one of the major environmental and climate issues for humanity nowadays. A standard precipitation evapotranspiration index (SPEI) was used in this study to examine the drought evolution characteristics of the Wei River basin. Yearly and seasonal SPEI values have been calculated for each of the 21 meteorological stations in this basin, using the long series of precipitation, temperature and sunshine hours from 1960 to 2013, and the trend of yearly SPEI analyzed. We adopted methods of Mann-Kendall test, accumulative anomaly and ordered clustering to diagnose the mutation characteristic of yearly SPEI, and obtained a drought coverage and drought distribution characteristics of the basin. Results showed an overall decreasing trend in yearly SPEI with a mutation occurring in 1990, revealing a drought intensity increase in the basin from the level in 1960-1991 to a higher level in 1991-2013. The drought coverage for all the time scales in 1991-2013 except winter drought was higher than that in 1960-1991, and especially it was subjected to more rapid changes in spring. In 1991-2013, the frequency of moderate to severe drought was significantly higher than that in 1960-1991 and the frequency of continuous drought was also higher, signifying a condition of drought intensifying since 1991.