A vessel-based line-transect survey was conducted monthly during 2007-2008 to assess the distribution, seasonal movement pattern, and population structure of the Chinese white dolphins () in the western Pearl River Estuary (WPRE). Most sightings of the dolphin occurred in the waters of <10m depth between south Sanzao and west Dajin Islands, and the 20m isobath may be the southern boundary of the dolphin occurrence in the WPRE. The dolphins tended to move north to the shallow waters in the wet season, whereas they swam south to the deep waters in the dry season. The seasonal north-south movement patterns in the WPRE was opposite to that in the eastern Pearl River Estuary (EPRE). Encounter rates of dolphins in the WPRE were high in the wet season but low in the dry season, and the result of correlation analysis between the parameters of individuals/100km based on month in the WPRE and Lingding Bay of EPRE showed significant negative correlation ( < 0.05), which may imply the individual exchanges between the western and eastern estuary alothough there were still no direct evidences. Comparing dolphin encounter rates recorded in this study and the studies in the EPRE (including Lingding Bay and nearby waters, Hong Kong waters) demonstrated that the WPRE waters was also one of the most important habitats of Chinese white dolphins in Pearl River Estuary. Further studies are necessary for more clearly understanding the population biology of the western population and its relatioship with that in the eastern part, in order to more effetively protect this animal in Pearl River Estuary as a whole.