Abstract: The diet composition of jellyfish is a key issue of feeding ecology research. This paper used high-throughput DNA sequencing technique to identify the food composition of Sarsia tubulosa and Rathkea octopunctata, in situ. The results showed that the food types of Sarsia tubulosa and Rathkea octopunctata were multitudinous. The Sarsia tubulosa predated 31 different species, while the Rathkea octopunctata preyed 29. In term of food composition, the two species of jellyfish were omnivorous organisms, included zooplankton, fungi, phytoplankton, terrestrial plant detritus and so on. The Sarsia tubulosa and Rathkea octopunctata were mutual predators. The food groups of 2 species were similar. Arthropods and Maxillopoda were the most frequently observed phylum and class in the food of both Sarsia tubulosa and Rathkea octopunctata. The dominant species was Eurytemora pacifica, which accounted for 45.14% and 42.42% of the food source, respectively. The utilization of high-throughput sequencing technique is a new and useful tool for studying the diet of jellyfish in situ, and the food composition resulted from 2 jellyfish provides a significant reference for jellyfish feeding ecology.