Abstract: Based on the daily data from108 meteorological stations in Southwest China during 1960 to 2011, as well as use of the monthly potential evapotranspiration and monthly precipitation data, the surface humidity index was calculated. The temporal and spatial variation characteristics of surface humidity index were analysized by using the methods of Inverse Distance Weighted interpolation in ArcGIS 9.3, moving t-test technique, climate tendency rate and Morlet wavelet. The results show that: in recent 52 years, the surface humidity index in Southwest China is decreasing in fluctuation and the decreasing rate is -0.005/10 a, which showed the slightly trend to drought. The 1990s have the greatest increase in change to wet and the anomaly value is 0.106. The 21st century witnesses the most significant increase in desiccation and the anomaly value is -0.052. Especially after 2002, surface humidity index drops significantly, the minimum value appears in 2009 and the anomaly value is 1.41. Annual humidity index exists obvious differences in space. The surface humidity index not only decreases from southeast to northwest, but also from south to north. Western Sichuan Plateau and the Yunnan-Guizhou Plateau are the low center value while the high value center is in the western Sichuan Basin. The area turning to be dry is larger than to be wet in the study area, correspondingly, the process of turning to be dry is more obvious than that of wet. Abrupt change analysis and Morlet wavelet power spectrum analysis indicated that surface dry and wet conditions in Southwest China have abrupt change events in 1990 and 2003 with a period 10.638 years.