The Changjiang Estuary is the largest estuary on the west shore of the Pacific, where a number of different water masses, including the Changjiang River plume, China Coastal Current and Taiwan Warm Current, meet and interact to each other. In addition, the Changjiang Estuary is an important source of nutrients to the East China Sea, and the most important and sensitive habitat of many brackish water and marine species as well. As an important component of benthic ecosystem, meiofauna are considered to be energetically important in benthic food web, and they play a role in the recycling of nutrients. On the other hand, as significant environmental bioindicators, the environmental monitoring function of meiofauna has drawn more and more attention. A quantitative study of meiofauna was carried out in Changjiang Estuary and its adjacent continental shelf waters (121-128.0°E, 29.5 -32.5°N) in spring, 2007. Samples were collected using a multiple corer with four tubes of 95cm in diameter, and only undisturbed cores with clear overlying water were used. The results showed that there were a total of 18 taxa of meiofauna in the surveyed area, and the average abundance was （1117.19±820.36 ）ind/10cm2, and the average biomass was （754.87± 546.37）(μg?DW)/10cm2, among which free-living nematodes were unquestionably the most dominant taxon, constituting 94.64% of total meiofauna abundance and 55.48% of the total meiofauna biomass. The other dominant groups were copepods, polychaetes and kinorhyncha. The study of spatial distribution has shown that high values of abundance and biomass occurred at stations alone 31°N, and the low values occurred within the Changjiang Estuary. The study of vertical distribution has shown that the abundance of meiofauna tended to reduce with depth, and 65% of the meiofauna was in the top 0-2cm layer. This vertical distribution pattern was also true for each of the dominant groups, with 64% of nematodes, >88% of copepods and about 61% of polychaetes found in the 0-2cm layer, respectively. Geographically, the highest total abundance of meiofauna occurred in the offshore waters of the continental shelf of the East China Sea, followed by the nearshore of Changjiang Estuary and Hangzhou Bay in descending order. The average concentrations of chlorophyll a and phaeopigment in the top 10cm sediment were (0.544±0.459) μg?g-1 sediment and (2.349±1.973) μg?g-1 sediment respectively, in which the concentration decreased gradually from the surface to the deeper layers. The results of correlation analysis with environmental factors indicated that there were significant positive relationships between salinity and the abundance and biomass of meiofauna, as well as the abundances of the dominant groups, i.e., nematodes, polychaetes and copepods. Dissolved oxygen near the bottom was significantly negatively correlated with the abundance and biomass of meiofauna and the abundances of polychaetes, nematodes and copepods. However, the median particle size and the contents of sand and slit-clay in the sediment had no significant relationship with the abundance and biomass of meiofauna and its major groups, nor were there significant relationships between the contents of chlorophyll a and phaeopigment in the surface sediment and the abundances of meiofauna, nematodes, polychaetes and copepods.