Island is the land in the sea.An intact island contains the adjacent sea area besides island terrene, insular shelf and offshore barrier.The area of island is small and its regional structure and ecological structure is simple.The ecological system of island is weak and the biodiversity index of island is very small.The stabilization of island’s ecological and environmental is not optimistic.A lot of ecological and environmental problems will be very easy to appear, if not being paid attention to protection the island.Major function oriented zoning emphasizes division and layout of the territory spatial development, and it requires the complete overlay of the territory.The island county is a compound system of territory.As the land area county, on the basis of the analysis on the resources environmental carrying capability, existing development density and future development potentials, considering the future of Chinese coordinate development of the distribution of population, economic layout, land use and urbanization patterns, the island counties can also be divided into four types of function zones:optimized exploitation zones, prioritized exploitation zones, limited development exploitation zones and banned exploitation zones.Based on the theories of major function oriented zoning and marine functional zoning and the quantification methods of AHP, multi-index synthetic weighed method, principal component-cluster analysis, considering the land and sea area factors, the paper combines qualitative analysis with quantitative analysis to integrate the geographical space thought into the analytical framework and make the major function oriented zoning of island county including the land and sea of Yuhuan and Dongtou counties.At the same time, this paper makes major function oriented zoning of the land and sea natural and compatible, and it makes the orientation of major function harmonious.