The copepod Calanus sinicus is one of the most important members of the marine zooplankton in the continental shelf oceans around China, Japan and Korea.While C.sinicus is widely considered to be herbivorous, information on its natural diet is very limited.In recent years, DNA-based methods have been used to obtain detailed information on the natural diet of small organisms such as inserts and molluscan larva.In this study, the natural diet of C.sinicus is obtained by DNA extraction of gut contents, PCR amplification, Illumina sequencing, and sequences analysis.Adults and C5 copepodites of C.sinicus were collected from coastal seas in southeastern Hong Kong (4 adults + 4 C5) and northern Taiwan (8 adults + 8 C5).