Abstract: The Pearl River Mouth Basin is an important petroleum base in the South China Sea. A number of shelf breaks have been distinguished for the depositional systems in the Pearl River Mouth Basin on the basis of 2-D seismic data throughout the whole area, including erosional, sedimentary, fault and flexure slope break zones. These slope break zones have generally migrated northwards since 30 Ma. During the Palaeogene to the middle stage of early Miocene, the small-sized slope break zones predominated, and once had an important effect on the delta and fan delta shallow-water deposits. From the middle stage of early Miocene onwards, the continental shelf break zones have been accentuated, and have exerted the influence on the shelf-margin delta and submarine fan deep-water deposits.