Vatica mangachapoi belongs to the Vatica Linn genus of the Dipterocarpaceae family and was once extensively distributed over Hainan Island, from low to medium altitude. It is now an endangered species and a Ⅱ grade key protected plant in China,due to over cutting for its valuable wood. It exhibits several excellent characteristics, such as strong adaptability to growth conditions, especially having the ability to colonize poor sandy beach or rocky areas, eventually easily forming a single Vatica mangachapoi dominant community due to strong natural regeneration, ability to compete and strong wind resistance. Therefore, it is no surprise that the Vatica mangachapoi forest is distributed over the sandy beach of Shimei Bay, Hainan Island, China, and is the only patch of natural forest growing on sandy beach environments in Hainan Island. Now it has become a significant model forest for the regeneration and transformation of manmade shelterbelts and as a scenic forest in the Shimei Bay tourism area in Hainan Island. The reproductive phenology study of Vatica mangachapoi forest will help to reveal the biological characteristics of Vatica mangachapoi that allows it to successfully settle and reproduce in arid coastal beach environments. Our primary objectives were to: (1) Investigate the biological characteristics of Vatica mangachapoi reproductive phenology, and (2) analyze the response of Vatica mangachapoi reproductive phenology to temperature changes in the coastal Vatica mangachapoi forest of Shimei Bay, so as to supply a theoretical basis for the protection and management of the Vatica mangachapoi forest and to predict Vatica mangachapoi fluorescence, formation of red seed calyx, seed rain dispersal periods, etc. The reproductive phonological observations were conducted on the three levels of population, individuals and twigs continuously for three years. Thirty individual Vatica mangachapoi were selected based on systematic sampling and sixty twigs were labeled with two twigs per individual. 3a meteorological data were obtained from Hainan meteorological Bureau to analyze the interannual phenophase variation. The results showed that the average reproductive phenophase, numbers of buds in a twig, seed setting rate of young seeds, and seed setting rate of mature seeds of Vatica mangachapoi were 101d, 133.3, 42.4% and 4.4%, respectively. The population of Vatica mangachapoi was of 1a continuous flowering type, but exhibited the obvious concentrated florescence with a bimodal. There were many flowers in the period of concentrated flowering and few in the non-concentrated flowering period; the flowering time exhibited an obvious asynchronicity among individuals and between twigs on each individual. There was a significant difference in the numbers of flowers and seeds between the harvest and lean years; the rainfall in one month before buds occurred had no obvious effect on the flowering phenophase, but the monthly average temperature did have an obvious effect. When the monthly average temperature in March and April in the month before buds appeared was higher than 24℃ and 26.4℃, respectively, the flowering phenophase progression was obvious, but the flowering phenophase was delayed when the temperature was lower. These results demonstrate that the response of the flowering phenophase progression and delay based on the rise and fall in temperature was nonlinear, and the bimodal phenophase and seed dispersal period were a benefit to successful Vatica mangachapoi seed germination and growth on the seasonal dry sandy beach.