Rocky desertification is one of the three major problems of land degradation in southwest China,and has long been a focus issue in academic circle.Rocky desertification may lead to the decline of water conservation capacity of the top soil,water shortage and low land productivity,which helps to accelerate the process of regional poverty.Thus,the knowledge of its distributive characteristics and development trend is of great significance for our scientific understanding and control work.Based on the data of the remote sensing images in Shizong county in 1995,2005 and 2015 respectively,this paper gives an analysis of the regional space-time change of rocky desertification in the past two decades by using the method of the decision trees to extract the distribution data of rocky desertification (6 grades are included:zero,potential,light,moderate,intensive and high-intensive). The spatial and temporal dynamic model of rocky desertification and the transfer matrix are used.The study results are as follows:(1) On time dimension,there is a great reduction in the potential,light and moderate rocky desertification,also a reduction in the intensive and high-intensive rocky desertification,but in a small range.There are increases both in zero desertification and the dynamic degree of integrated rocky desertification.Besides,a significant change in the dynamic degree of potential and mild rocky desertification can be found.(2) On spatial dimension,the severely-stricken areas of rocky desertification are mainly distributed in the following towns:Longqing,Wulong and Zhuji.As some distinctive features in the spatial distribution pattern,rocky desertification in these regions covers a wide range and complete grades.Meanwhile,in the central part,it shows a weak distribution grade of the linked rocky desertification areas.In the western and eastern parts,it presents a character of continuous distribution in moderate,intensive as well as high-intensive rocky desertification.