Abstract: The average reflectivity of tropical forest in Jianfengling, Hainan Island, is about 17.4% of the radiation, the effective longwave reflected radiation from tree crowns is about 13.7%, and the net radiation is about 70%. The evapotranspiration is about 36-57% of annual precipitation with an average value of 43.6%. The components of water balance, CO2 released from soil, and the property of forest microclimate obviously change with dry and wet seasons. The annual average of total litters of mountain rain forest and semi-deciduous monsoon forest are 7.7±1.2 t/ha and 9.7±2.3t/ha respectively. The material circulation study shows that the tropical forests have large return and higher decomposition of organic matters, less output of nutrient from ecosystem for maintaining the recycle utilization inside ecosystem undar the condition of less disturbance.