Based on the remote sensing images, meteorological and land use data of the Wudinghe River basin during 1982-2010, we used Priestley-Taylor formula to calculate potential evapotranspiration, then got aridity index of this period. With overlaying the meteorological factors and aridity index difference, pixel-by-correlation analysis, the aridity index variations over spatial and tempo - ral in the study area during this period were analyzed, and the influence of the climate and land use variations on the aridity index changes was studied. The results show that: (1) The aridity indexes of the year 1982 and 2010 were 2.01and 2.13 respectively. The trend was drought; (2) There was a rapid decline in the regional aridity index of 2.0 or less, while a significant expansion of the area above 2.15; (3) It showed an increasing trend with the aridity index, a significant increase in the region focused on the middle reaches and downstream areas of the Wudinghe River basin; (4) The variation of aridity index was positively correlated with the changes in temperature, vapor pressure and net radiation, while negatively correlated with changes in precipitation; (5) The aridity index of all the land use types showed a growth trend, but the growth rate was different: forestland > cultivated Land > pasture > building land> water body > unused land; (6) The impact of land use to the average aridity index was very weak, and the variation of aridity index was mainly caused by climate change.