Abstract: The composition and diversity of ichthyoplankton species in the Yangtze estuary and adjacent waters (30°45′–32°N, 121°–123°20′E) were analyzed based on four seasonal surveys during 2007. A total of 6,463 individuals, representing 12 orders, 28 families and 45 species, were collected. Engraulidae was the most abundant family comprising 76.5% of all teleost fishes. The ichthyoplankton community was composed of four ecological guilds: freshwater (2 species), brackish (14 species), coastal (10 species) and marine (16 species), of which marine species was the most abundant (74.6% of total abundance). Engraulis japonicus, captured every season, contributed most to total ichthyoplanton abundance. Species composition varied be-tween seasons; in spring, Allanetta bleekeri was the dominant species, while in summer E. japonicus domi-nated, autumn dominant species were E. japonicus and Hemisalanx prognathus. These dominant species contributed more than 89% of total catch in different seasons. Species number, abundance and diversity peaked in summer, were lower in spring and autumn, and were least in winter. These seasonal variations likely resulted from both migration associated with fish spawning and the environment.