Densities of major meiofaunal taxa were investigated at 34 sampling stations during six cruises by R/V Beidon to the stuthern Yellow Sea. China from 2000 to 2004, and the community structure of free-living marine nematodes was studied during one of the cruises in 2003. Meiofauna abundance ranged from 487.4 to 1655.3 individuals per 10cm2. Nematodes and harpacticoid copepods were the two most dominant groups. Contributing 73.8-92.8% and 3.5-18.7%. respectively to the total meiofauna abundance. One way ANOVA showed no significant annual fluctuation of meiofauna and nematode abundances from 2000 to 2004 in the southern Yellow Sea. However, two way ANOVA based on six stations sampled in 4 years (2002-2004) showed that there were significant difierences among the six stations and the 4 sampling years for meiofauna, nematode and copepod abundance. Conelation analysis demonstrated that meiofauna abundance was mainly linked to chloroplastie pigments. Other euviconmental factors could not be ruled out, however. A total of 232 free-living marine nematode species, bekonging to 149 genera. 35 families and 4 orders, were identified. The dominant species in the sampling arca were the following: Donylaimopsis rabataisi, Microluimus sp.1. Prochromadorella sp., Promanohystera sp., Cobbia sp. 1, Daptonema sp. 1, eptotaims sp. 1, Hatataimus sp.2, Aegiataataimus sp., Chromadorita sp., Parodontophora narina. Parasphaerolations paradoxas. Qundricoma sp. 1, Compylaimus sp. 1, Halalainus gratilis, Parame sacanthiop sp. 1, Putunonohystera sp. 1, and Metalinhomoens longixseta .CLUSTER and SIMPROF analyses revealed three maia types of nematode community (or station groups) in the sampling area, including 1: coastal community. H: transitory community betwcca coastal and YSCWM (Yellow Sea Cold Water Mass), and III: YSCWM community. Each community was indicated by a number of dominant nematode species. Bio-Eny conelation analysis between the mematodc community and cnxirommental variables showed that water depth, sediment water content. Organic mather, chlorophyll a (Chl-a) and phacophorbide a (Pha-a) were the most important factors to determine the commurity structose.