Abstract: To evaluate unbiasedly the dynamic situation of ecological security in the process of largescale urbanization in Pingtan Island. It is of great significance to realize the coordinated development of island development and ecological environment. According to the actual situation of Pingtan Island, 34 evaluation factors were screened out with Delphy method, and the ecological security evaluation index system was constructed. The combination weights of entropy weight and variance coefficient are calculated by entropy weight method and coefficient of variation method. The grey relational grade of ecological security was calculated by means of correlation coefficient average method and weighting method respectively. The ecological security status of Pingtan Island in 2005～2015 was evaluated dynamically to enhance the objectivity and accuracy of evaluation results. According to the average correlation, the ecological security situation of Pingtan Island was found to be critical in 2006～2009. Among them, the average correlations in 2007 was the smallest, with value 0.570 0 only. After the officer establishment of the Pingtan general experimentation area in July 2009, furnished with the development funds, more and more attention has been paid to the coordination between island development and environmental protection. In 2010～2015, the ecological security situation of the island was in the state of good condition. Among them, the average correlation reached 0.825 9 in 2011, and the ecological security situation was in an ideal condition.