Abstract: The forest ecosystem is the core of the integrated ecosystem that includes the economic ecological security, the social ecological security and the natural ecological security. Forest ecological security for island is the security of the integrated ecosystem. Base on history research and related literature, the forest ecological security assessment’s index system and the markvalues are formed. Using entropy weight and experiences, the weights are conformed. The integrated ecological security indexes are gained by integrating index evaluation method. Xiushan Island was taken as a case study and its forest ecological security, pressure, state, response situation from 1990 to 2007 is found. From 2003, forest ecological security index is increasing, and it is 0.42 in 2007. Its developing tends and the reasons are analyzed in paper. It shows the utility of the human pressure is more useful than the utility of the natural pressure and the utility of human response is not enough. Finally, some suggestions are proposed for the forest ecological security improvement.