Abstract: In this paper, the values of aridity index in China were calculated using the time series 2.0 climatic datasets from Climatic Research Unit of University of East Anglia and the Holdridge potential evapotranspiration method. On which the dynamic change of values of aridity index in China in the 20th century was analyzed. Moreover, the results were interpolated in GIS software, and then they were formed as the digital maps of AI distribution in China. The results show that there was a notable reduction of humid climate area in China in the 20th century, semihumid climate area was enlarged considerably, dry climate area was enlarged significantly, and the drought trend was significant. Temperature increase and precipitation decrease in China leaded to a reduction of surface moisture and a disadvantage for moisture accumulation over land surface. These are the important factors of producing and aggravating ariditification.

Key words: aridity index, potential evapotranspiration, climatic change, ariditification, desertification