Abstract:An analysis of population biology and genetic diversity of Macaranga sampsonii was taken in DHS-20-hm2 permanent plots,which locates on the Dinghushan natural reserve. By use of point pattern analysis and DBH-class structure analysis,it was concluded that M.sampsonii was a light-dependent egy,whose population age structure was approximately pyramid-like. The population habitat was restricted in the canopy gaps because of sunlight deficiency stress. Thirteen microsatellite loci were isolated by methods of magnetic beads enrichment,in which only two loci(15.4%)were polymorphic. The polymorphic information content of these loci ranged from 0 to 0.3734.The average expected heterozygosity of M.sampsonii was 0.0756,which was obviously lower than other Macaranga species. These results indicated that M.sampsonii was in a narrow environment adaptation range and a low population genetic diversity. We should take measures to evaluate and protect its germplasm resource.