The meiofaunal abundance and biomass in the Changjiang (Yangtze River) Estuary and adjacent waters was evaluated based on samples collected from July 13 to August 30, 2006. The group composition, the horizontal and vertical distribution of abundance and biomass, environmental factor were analyzed. A total of 11 meiofauna groups and Naupius were found from the surveyed area, including Nematodes, Copepods, Polychaetes, Oligochaetes, Ostracoda, Acari, Bivalves, Gastrotricha, Kinorhyncha, Amphipods and Isopods. The results showed that average abundance was 453.22±355.34 ind/10 cm2. Nematode accounted for 81.37% of the total abundance of all meiofauna, followed by Copepod (10.13%) and Polychaetes (2.96%). The average biomass of the meiofauna was 622.65±505.07 μg/10 cm2. Polychaetes accounted for 30.21% of the total biomass of all meiofauna, followed by Nematode (23.69%) and Oligochaetes (19.44%). The horizontal distribution showed that the meiofaunal abundance increased from the estuary to the East China Sea Shelf. The average abundance in the Hangzhou Bay was 240.96±223.47 ind/10 cm2. The average abundance in the Changjiang Estuary was 442.91±304.16 ind/10 cm2. The average abundance in the East China Sea was 865.42±553.88 ind/10 cm2. The analysis of vertical distribution showed that the abundance of meiofauna decreased with the depth in the sediment. The highest abundance of meiofauna was 290.28±250.03 ind/10 cm2 in 0-2 cm layer. The second highest abundance of meiofauna was 132.81±128.74 ind/10 cm2 in 2-5 cm layer. The lowest abundance was 30.14±31.91 ind/10 cm2 in 5-10 cm layer. The Nematodes, Polychaetes, Oligochaetes, Copepods had the same vertical distribution trend. The correlation analysis of environmental factors indicated that dissolved oxygen, depth and salinity were the main factors to influence the meiofaunal abundance in the surveyed area. Result of BIOENV analysis showed that the best combination of environmental factor was dissolved oxygen and salinity.