Based on daily meteorological data of 18 observations from 1961 to 2001 within Guizhou Province, Mann-Kendall trend test, correlation analysis and principal component analysis were applied to determine trend of pan evaporation and its relation with meteorological factors (net solar radiation, temperature, relative humid, wind speed etc.). Analysis results demonstrate: pan evaporation presents a significant decrease trend in the 41 years (99% confidence level). This decrease trend is especially more significant in winter, spring and summer seasons. Spatially, significant decrease of pan evaporation occurs in the east area and part of the west area, and seldom occurs in the other areas. The pan evaporation decrease is primarily resulted from reduction of net solar radiation.