Abstract: A total of 11 pairs of SSR primers were applied to study the genetic diversity of five sympatric populations of Camellia meiocarpa and C. oleifera, the populations’ genetic structure, and the interspecific introgressive hybridization. The alleles shared by the two species were 57, accounting for 96.6% of the total. There were two specific alleles in C. oleifera, but no specific alleles in C. meiocarpa. Certain difference was observed in the phenotypic frequency between the two species, and the intraspecific genetic diversity of the two species was high. At species level and population level, the polymorphism information content of the two species was between 0.25 and 0.50, suggesting that the genetic polymorphism was moderate. The mean value of genetic differentiation among the sympatric species was 0.057, being obviously lower than that of the foreign species (C. meiocarpa 0.332; C. oleifera 0.201) and of xyloid angiosperms (0.102). The mean value of gene flow among the sympatric species was 10.072, which was significantly higher than that among the foreign species (C. meiocarpa 1.006, C. oleifera 1.990). The UPGMA cluster results showed that the genetic relationship of the two species was very close to, meaning that there existed an obvious interspecific introgressive hybridization. C. meiocarpa was possibly a variety of C. oleifera as a result of the introgressive hybridization.