The Pearl River Delta Economic Zone, which lies in the central south of Guangdong Province and borders on the South China Sea, has experienced strong land-sea interaction and active neotectonism as well as obvious erosion, and is characterized by wide distribution of Quaternary sediments and a variety of landform types. It is a transitional zone and a sensitive belt of geological environment. Based on current survey and past research findings, the authors have summarized the main factors controlling geological environment, such as geomorpohologic landscape, neotectonism, change of sea surface and evolution of Quaternary sedimentation. From the angle of geological environment, some corresponding countermeasures are proposed.