Jintang Island, located in Zhoushan archipelago New Area, China, covers an area of ~76.4 km2. As the closest island to connecting the continental shore of Zhejiang and the eastern Zhoushan Island after the project of Zhoushan Tran-Oceanic Bridges, it has experienced great change during the past 40 years, and however little attention was paid to evaluate the coastline exploitation of Jintang Island. In this paper the coastline position was firstly extracted by combining histogram thresholding and band ratio techniques with visual interpretation supplemented, based on multitemporal medium-high resolution imagery from 1970 to 2011. And then the coastline exploitation degree for different periods was quantified from three index, coastline complexity, coastline artificial intensity and coastal use. The uncertainty for coastline extraction was controlled in one-pixel for each image. The results show that the position of coastline accreted seaward since 1970. As the natural coastline was straightened, the proportion of artificial coastline has surpassed the natural coastline after 1992. Until 2011, the dominant coastline type has been changed as artificial coastline, mainly covering urban/industrial and port coast. The calculated coastline exploitation degree of Jintang Island in 1970, 1992, 2003 and 2011 is 0.637, 0.719, 0.734 and 0.929 respectively, showing an uptrend. Part 1, 3, 4, 5, 7 and 8 of the total coastline are relatively higher than other parts, and this generally coincides with the distribution of deep ports. It indicates that natural conditions and human policies may contribute to increasing coastline exploitation from 1970 to 2011. And Jintang Island is facing great human intervention for reclaiming more coastal land to develop the marine economy.