The South China Sea is the largest semi-enclosed marginal sea in the Western Pacific.It is also a core area affected by the Southeast Asian monsoon. Due to its special geographic location, the hydrological characteristics are extremely complex in the northern South China Sea. In summer, driven by the southwest monsoon, there are seasonal coastal upwellings in the northern shelf of the South China Sea, which mainly include the coastal upwellings of East Guangdong and Qiongdong. In addition, the diluted water from the Pearl River Estuary with high nutrients also has an important impact on the ecological characteristics in the northern South China Sea.This study is based on the data collected from 23 stations set up in the northern South China Sea during summertime of 2012. The larval and juvenile fish samples were collected by the vertical trawl survey with WP2 plankton net (net diameter 57 cm, net length 271 cm, mesh 200 μm). The species composition and quantity distribution of larvae fish and juveniles were studied, and the association between them and environmental factors was investigated, and the correlation between the hydrological characteristics of the northern South China Sea and the distribution and assemblages of fish larvae and juveniles was analyzed. A total of 230 fish larvae and juveniles were collected, belonging to 11 orders, 33 families, and 77 species, of which 46 species were identified. The most diverse order was Perciformes, with 24 species in 16 families, accounting for 31.17% of the species of fish larvae and juveniles in the surveyed sea area. Followed by Myctophiformes and Stomiiformes, 18 species in 1 family and 12 species in 4 families, respectively. The fish larvae and juveniles of Myctophidae, Phosichthyidae and Gonostomatidae accounted for about 50% of the total catch of fish larvae and juveniles.These results are consistent with the results of many previous surveys, which indicates that the species composition of fish larvae and juveniles in the South China Sea has not changed much.The changes in the number of fish larvae and juveniles among the stations in the surveyed sea area are more consistent with the change trend of the richness index (D). In general, the fish larval and juvenile fish community structure in the surveyed sea area is relatively stable.In summer, abundance of fish larvae and juveniles was related to environmental factors, such as temperature, salinity, chlorophyll-a mass concentration. Three peaks of the abundance were found, in eastern Hainan Island,where the coastal upwelling occurred,the diluted water from the Pearl River, and coastal water of the Paracel Islands. At the same time, the canonical correlation analysis (CCA) results also showed that the temporal and spatial distribution of fish larvae and juveniles in the northern South China Sea is closely related to surface sea temperature (SST) and chlorophyll a (Chl.a) mass concentration.Cluster analysis showed that the fish larvae and juveniles assemblage could be divided into oceanic group and offshore group.