Diversity of demersal fish in the Sea of Vietnam was analysed using the trawl survey data collected in periods from 1996 to 2005. There was 355 demersal fish species identified belongs to 196 genus in 98 families of 21 orders. The Southeast water was the most diversified whereas the Southwest water, was observed poorest in term of species composition. Distribution of demersal fish species was area specific. Also, there are some species distributed widely, found in all the sub-area of Vietnam sea. The orders Perciformes, Scorpaeniformes, Pleuronectiformes, Anguilliformes and Tetraodontiformes were the most richness. In term of genus diversity, the abundance families were Sciaenidae, Gobiidae, and Platycephalidae. The Shannon - Weiner index (H') of the demersal fish community were estimated in the ranges from 0,74 to 1,70
1,25-1,81
1,24-1,57 and 1,191,69 for the Tonkin Gulf, Central Area, South East Area and South West Area, respectively. It is indicated that the demersal fish community was variable by time and by space. Stock biomass of demersal fish in the Sea of Vietnam (not included biomass of the less than 20m depth strata) was estimated approximately 350 thousand tones, appropriated about 30 percent of the total trawlable biomass.