The world is undergoing the largest wave of urban growth in history. More than half of the world's population now lives in towns and cities, and the proportion of the global population in urban areas has increased conspicuously from 30% in 1950 to 54% in 2014. Urbanization is projected to increase even further to 60% in 2030. Though the process of urbanization provides comfortable and convenient living conditions for human beings, it also makes our country face a series of serious urban ecological security issues (such as environmental pollution and diminishing resources) because of the high-intensity of human activities and unreasonable land use. Nowadays, urban ecological security brought by the rapid urbanization is posing a serious threat to urban sustainable development. Against this background, constructing the urban ecological security pattern is the basic guarantee and important way to realize regional and urban ecological security. Based on the eco-environmental background conditions of Pingtan Island, this study first investigated the perspective of urban ecological security and considered the overall plan of Pingtan Comprehensive Pilot Zone to better understand six key ecological sensitive factors that were closely related to the urban ecological security of Pingtan Island. These six key ecological sensitive factors were drinking water resources, coastal shelterbelt, scenic spots and forest parks, natural mountain, cultivated land, and coastline resources. Thereafter, a comprehensive evaluation model was established by the analytical hierarchy process (AHP) and geographical information system (GIS) spatial overlay method to comprehensively evaluate the ecological sensitivity of Pingtan Island. The specific analysis process was as follows:First, an evaluation index system of Pingtan Island's ecological sensitivity by means of data collection, field investigation, remote sensing image interpretation and analysis, and expert reviews was established. These indices were classified according to their sensitivity. Second, the judgment matrix was constructed and consistency checks were performed in accordance with the AHP method, then the weight of each index was calculated according to the square root method. Finally, considering that scenic spots covered with natural mountain forest have the highest ecological sensitivity, and that other areas may not be ecologically sensitive or may be insensitive, the Pingtan Island was divided into five grades (extreme sensitivity, high sensitivity, moderate sensitivity, low sensitivity, and insensitive grades) according to their respective ecological sensitivity indices. We propose an ecological security pattern for Pingtan Island in order to adapt to the new round of large-scale urban development boom, and this pattern is mainly composed of ecological security barrier ring, ecological water system, ecological conservation area, ecological coastal zone, urban construction area, and the ecological promotion area. These components play different roles in maintaining ecological safety on Pingtan Island, and they must be rationally developed and utilized on the basis of their respective functions. Generally, the results of this study would help to provide decision support for urban planning, and could be of great theoretical and practical significance to maintain Pingtan Island's ecological security and promote the sustainable development of Pingtan Island. Moreover, these results may also be useful for ecosecurity pattern research on other island cities.