基于遥感影像与地理信息系统技术对比了1980年代—2010年代中国防城湾与越南海防港的海岸线及围填海变化情况。30多年来，两地海岸线均以向海迁移为主，其中防城湾海岸线平均端点变化速率为6.49 m/a，海防港为6.21 m/a，分别呈现先升后降与先降后升的变化趋势；在1980年代和1990年代，平均端点变化速率为防城湾大于海防港，在2000年代和2010年代则相反。防城湾和海防港年均新增围填海面积分别为122.48 hm²/a和164.24 hm²/a，围填海强度指数均呈不断上升的趋势，其中在1980年代和1990年代防城湾小于海防港，在2000年代和2010年代则相反。从1980年代至2010年代，围填海面积与年均空间扩展速率两指标，在防城湾呈先增加后下降的趋势，在海防港则呈持续波动状态。围填海为两地海岸线变化的主要因素，港口建设是其最主要的驱动力。

Based on remote sensing images and geographic information system technology, the coastline and reclamation information of Fangcheng Bay in China and Haiphong Port in Vietnam from 1980s to 2010s were compared. The results showed that in the past 30 years or so, the coastline of the two places mainly migrated to the sea, of which the average end point rate of Fangcheng Bay was 6.49 m/a, and that of Haiphong Port was 6.21 m/a, showing a trend of rising first then falling and falling first then rising, respectively. In the 1980s and 1990s, the average end point rate of Fangcheng Bay was higher than that of Haiphong Port, while in the 2000s and 2010s, it was the opposite. In the past 30 years or so, the average new reclamation area of the two bays was 122.48 hm²/a and 164.24 hm²/a, respectively, and the reclamation intensity index of the two places showed a rising trend. In the 1980s and 1990s, the reclamation intensity index of Fangcheng Bay was smaller than that of Haiphong Port, while in the 2000s and 2010s, it was the opposite. From 1980s to 2010s, the reclamation area and the average spatial expansion rate per year increased first in Fangcheng Bay and then decreased, while Haiphong Port continued to fluctuate. Reclamation was the main factor for the change of the coastline of the two places, and port construction was the main driving force.