On the basis of the natural superiority of Hainan Island, this paper using the agroecological method of climatic potential productivity which FAO introduced in "the Relation between Production and Water":calculated the climatic potential productivity of rice. And on the basis of the present situation of the production of. rice and the population of Hainan Island, it using the GM(1, 1) forecast mold in the grey system:calculated and investigated the problem of population bearing capacity of the production of rice at present and in the future. It tries to reveal the present situation, problems, and prospects of development of the production of rice to provide a scientific basis for production, consumption, and purchase of rice in the Island.