Belanger's croaker (Johnius belangerii) is a fundamental fish species of family Sciaenidae which usually has high gastric vacuous rate during 24 hours trawl surveys making the diet analysis difficult to continue. However, it plays an important role in the predator-prey relationship in the food web of Ma'an Archipelago, East China Sea. In this study, we use visual inspection with DNA barcoding technology combined previous collected data to make more comprehensive analysis towards its diet compositions and realistic prey-predator relationships. We amplified mitochondrial cytochrome oxidase subunit I (COI) using fish and invertebrates universal primers in sampled fish stomach contents which could not be identified by morphological observation. Our results indicated that using DNA barcoding could successfully identify those partially digested food compositions species, such as Solenocera crassicornis, Alpheus distinguendus, Palaemon macrodactylus, Alpheus japonicus, Acetes chinensis, Sebastiscus marmoratus. We found belanger's croaker mostly feeds on shrimps (frequency of occurrence, 45%) and crabs (23%), some juvenile fishes (27%) occasionally and among them S. crassicornis, P. macrodactylus, Portunus sanguinolentus, Oratosquilla oratoria had not been observed in summer investigation ever before. In conclusion, the accurate and sufficient diet analysis is the precondition of feeding habit research which could contribute to reasonable suggestions of the management of island reef area ecosystem and fisheries forecasting.