Abstract:By PCR products sequencing methods,nuclear ribosomal DNA ITS regions of nine samples of Sargentodoxa cuneata and one sample of S.simplicifolia were sequenced and analyzed. The results showed that the ITS length of S.cuneat and S.simplicifolia was from 634bp to 635bp. The ITS1 was 163bp and the ITS2 was from 238bp to 239bp. Based on the maximum parsimony(MP)trees as Sinofranchetia chinensis was the outgroup,all the ten samples of S.cuneata and S.simplicifolia formed a monophyletic clade and got 100% bootstrap support. According to the present distribution of S.cuneata and S.simplicifolia in China,the apperancance of S.simplicifolia in Shaanxi Province,as well as the analyzed results of molecule data,the flora of Central China was probably modern distributing center of S.cuneata. The distribution of S.cuneata presented zonal differentiation of the flora of Central China,East China and South-West China. The zonal differentiation was more related with the co-evolution of the geography,climate and environment and so on. The ITS length of the samples of S.cuneata and S.simplicifolia coming from Ningshan,Shaanxi Province was 635bp. Their pairwise divergence was only 0.003 2. Compared with other samples,at the same site in ITS2 of S.simplicifilia and S.cuneata(shaanxi)a base was transversioned,at another site a base was inserted. The ITS data showed their geography special. The pairwise percentage divergences in the sample of S.simplicifolia and nine samples of S.cuneata were from 0.32% to 2.31% and were much lower than the pairwise percentage divergences among species of most angiosperm,which were from 1.2% to 10.2%.So it would be better if S.simplicifilia was merged with S.cuneata based on ITS data.