Abstract20 278 species,belonging to 5kingdom and 44 phyla,have been recorded in China seas．Among them 12?phyla are exclusive marine species．The numbers of species in sea exesses that in fresh water and is less than??? that on the terrestrial and it increases northward．It covers the species from Warm-water,temperate-water??? to the cosmopolitan．The north marginal distribution boundary of many tropic marine organisms and the??south distribution of some temperate marine species is just delimited in China seas．