Abstract: Dipteronia dyeriana Henry is a rare and endangered species restricted in a small adjacent corner of Wenshan,Pingbian and Mengzi counties of Yunnan,southwest China.The genetic diversity of four natural populations was estimated using allozyme markers.Thirteen loci of eight enzyme systems were scored for the analysis of population genetic diversity and structure.A low genetic diversity was observed in this rare species,with a mean percentage of polymorphic loci P=15.4%,an average number of alleles per locus A=1.2,and an average of expected heterozygosity H_e=0.064.All populations deviated significantly from the Hardy-Weinberg equilibrium.Very slight population differentiation was detected(G_ST=0.099).Nei’s genetic identity ranged from 0.985 to 1.Moderate gene flow was inferred(Nm=2.669).According to the Unweighted Pair Group Method with Arithmetic(UPGMA)cluster analysis based on the genetic distance,Mengzi and Majiazhai populations are clustered in one clade and its genetic distances are positively related to the geographic disance.For conservation purpose,we strongly suggest strict protection of the natural populations of the species should be conducted,and ex situ conservation could be an effective supplement.