Based on the measured results from oceanographic survey carried out, in the East China Sea(26°30′-32°30′N、121°00′-128°00′E) in 1999 from June to October, this paper analyzed species composition and distribution of fish eggs and larvae and studied on the relationship with species composition and hydrologic environmental factors. According to the results，80 species were identified in the surveying waters，which be longed to 11genus, 52 families and 40 orders. Perciformes was the main predominant group of all genera, which was 48.75 percent of total numbers of species. All species were categorized into four ecological forms, such as brackish forms, eurythermic euryhaline forms，temperate euryhaline forms，and tropical halophile forms. Scomber japonicus and Engraulis japonicus were respectively dominant species of fish eggs and larvae. The numeral distribution of species was different on account of the different waters environmental conditions. The distribution was marked the boundary by 30 N. Its distributional characteristics showed that the value in northern was less than that in southern waters. As a result of water temperature in the majority of north waters was a bit lower; amount of some species that adapting well to lower temperature were reduced, Taiwan warm current and the kuroshio brought many tropical species with both high temperature and salinity into the south-east waters. It was the reason that the numbers in the northern was much less than that in the southern. The stability of species composition of larvae was inferior to fish eggs. The diversity index of larvae was higher than that of fish eggs; also the composition was more complicated than fish eggs. The interspecific uniformity was no symmetrical than fish eggs. The dominant species was obviously of larvae, the dominance value higher than that of fish eggs. The biodiversity index of fish eggs and larvae was affected by water temperature and salinity. The regression analysis of the relativity between H′ and water temperature, salinity showed that, the correlation coefficients between H of fish eggs and water temperature，H′ of larvae and water temperature and salinity were significant at 0.05 and 0.01 level respectively. H′ value was lower basically intensification of the Jiangzhe coastwise current, water commuted notability which resulted in species subrogation distinctly and community instability, in the southern offsea. As far as H′ value of the southern outsea was concerned, the kuroshio waters controlled perennially, waters condition diversification was less, the ecological system was steady, the same as the ecological groups construction, above-mentioned condition led to the value was higher.