The coastal zone has become the key area of urbanization with its rich natural resources and advantageously geographical location. This paper identified and analyzed the coastline length change of Guangdong-Hong Kong-Macao Greater Bay Area (GBA) under rapid urbanization based on high-resolution images of Google Earth platform in 2001, 2010 and 2018. We analyzed land use/land cover (LULC) change in the GBA coastal zone, and analyzed the correlation between the urbanization of coastal cities and LULC change of coastal zone. The results showed that (1) the coastline length of the GBA increased by 32.24 km from 2001 to 2018, indicating that the human activities had marked impacts on the coastline; the artificial coastline increased by 219.91 km, mainly at the cost of the decrease (187.67 km) of natural coastline. (2) and the urban land in the coastal zone (5 km buffer zone on the landward side of coastline) increased by 588.33 km² and mainly encroached agriculture (347.58 km²); (3) there were significant correlations between the urbanization level of coastal cities and the growth of urban land in coastal zones from 2001-2018, and the relation became stronger during 2010 to 2018 (R²=0.6851) than that during 2001 to 2010 (R²=0.437), suggesting that the effects of urbanization was deepened. Our findings have important practical implications for coastal zone protection, restoration and land use planning and management in GBA.