Abstract: Davidia involucrata,called the Chinese dovetree or handkerchief tree,is a relic deciduous species of Tertiary period.As the sole member of the family Davidiaceae,it is endemic to Southwestern China,but now also widely introduced elsewhere.In order to find out the relation between soil characteristics and optimal altitude for Davidia involucrate growth,a study of the rhizosphere soil characteristics and plant diversity of Davidia involucrate communities at different altitudes were finished.The study area was Bainigang Region of Wolong Nature Reserve and the obtained conclusions indicate that:plant diversity of Davidia involucrate community at 1700 m is the highest and the optimal altitudes for Davidia involucrate growth are from 1500-1700 m.Differences of soil characteristics among different horizons are significant which in terms of available phosphorus,available nitrogen,available potassium,organic matter and water content.The change of pH is little.In the region,as to the soil chemical property of humus horizon,the 1500-1700 m altitudes are remarkably higher than those of 1800 m and 1850 m altitudes.Among different altitudes,variation regulations of soil nutrient of illvuial horizon and parent material horizon soil layers could hardly be concluded.The pearson correlation shows that there is no relationship between the species diversity and available phosphorous,available potassium and pH.Only the organic matte of illuvial horizon and the moisture content of humus horizon are significantly correlated with the species diversity while the available nitrogen,moisture content of illuvial horizon and parent material horizon are significantly correlated with the species diversity negatively.