Abstract: Coastal Vatica hainanensis forest in Hainan is a special type of tropical rainforest. To analyze this community, we used methods of sampling area analysis, including both quantitative mathematical modeling and qualitative comparison. Eight mathematical models (species-area curves) were used to calculate the minimum sampling area and relevant coefficients. Importance values were derived to confirm the modeling consequences. Species diversity was also analyzed by various kinds of diversity indices. Results showed that the minimum sampling area of coastal Vatica hainanensis forest in Shimei Bay was 800 m2. This value of minimum sampling area was the lowest in global tropical rainforest types. Coastal Vatica hainanensis forest in Shimei Bay was a strongly mono-dominant forest with low species diversity. Thirdly, the pattern of tree layers in Shimei Bay, measured by the Gleason index, differed greatly from that of mountain rainforest on Hainan Island. The study revealed that Shimei Bay, Hainan Island hosts a natural rainforest climax community which has low species diversity and salient monodominant community characteristics.