Abstract: A light-purse seine is one of the main fishing gears in the marine capture fisheries of South China Sea. The proportion of the catch of juvenile species in this fishery has long been high, which has arrested the attention of fisheryadministrations and scientists. In order to find out the proportion of the catch of juvenile species in the light-purse seine fisheries and its effects on fishery resources, an investigation and analysis was conducted on the fishing ground along the coast of Yangjiang, Guangdong, in May and October, 2006. The results showed that there was a diversity in species and a high percentage of juveniles in the catch. The catches were mostly pelagic species, such as Trichiurus haumela, Decapterus maruadsi, Loligo spp., Trachurus japonicus, D.macrosoma, Rastrelliger kanagurta and Selar crumenophthalmus, etc. The catch of the juveniles in many species had exceeded the minimum legal percentage of allowable catch. The fisheries tended to damage the marine fishery resources in the northern South China Sea. It is recommended that the optimum length at first capture be established as early as possible for the main fishing species in the northern South China Sea, that the minimum mesh size be established for the bunt of the purse seine, that the optimal light intensity be regulated and that the optimizationas well asmanagement of the fishing gear be strengthened.