Large scale marine biodiversity studies in China have been carried out for more than half a century since the founding of the Institute of Oceanology, CAS, in 1950. Through a series of coastal and multi-disciplinary oceanographic investigations in the shelf seas and biodiversity studies since the late fifties, a total of 20,278 species of marine biota have been recorded upto 1994. Recent intensive studies have further revealed the richness of marine biota of the China seas,a great number of marine species have been found and many new taxa established. The total species number of main biotic groups increased about 50 % of that estimated in 1994. The results have promoted the fast development of China's marine fisheries, medicine (drug) and biodiversity research, and attracted many scientists, particularly bio-technologists, to join their studies. Environmental deterioration and human activity strongly stressed the sustainable development and conservation of marine bio-diversity, and resulted in the increase of end angered species as record ed in the new published ${\ll}$China Species Red List${\gg}$ with the threatened category of species assessed by adopting the new IUCN criteria. To further reveal the high diversity and their history, present status and future of marine organisms existed in the world ocean, an international Project ${\ll}$Census of Marine Life (CoML)${\gg}$ was established in 2000 in the USA. Scientists predicted that 2 to 3 times of numbers of the known species will possibly be found in various marine habitats, particularly the abyssal ocean. The Research Plan and the Projects were briefly introduced, and the relationship between marine biodiversity and biotechnology was discussed. The Project planned to apply new and high techniques and new equipments on board research vessel and in laboratory. Brief review of recent advances of Chinas' marine biodiversity and biotechnology studies indicated that fascinate results have been achcieved; but further effort should be made to promote the continuous advance of our basic researches and their application in related production and maintain sustainable development.