In recent years due to some new diseases and the emergence of bacterial resistance, the higher screening repetition rate of secondary metabolites from microorganisms, some metabolic genes not expressed in the laboratory conditions, it is necessary to find new microbial strains and activate genes of microbial metabolites. Marine animals harbor rich symbiotic microbial communities, which can produce many compounds with biological activities, and are potential medicinal resources. This paper reviews the research on the co-culture of marine microorganisms associated with marine animals (ascidians, sponges, corals and sea anemones) in recent years, including the selection of co-culture strains, the conditions of co-culture, the influence of quorum sensing and signal molecules on co-culture strains, and examples of co-culture among different kinds of microorganisms. Compared with single culture, the kinds of secondary metabolites or the biological activity of secondary metabolites or the productions of secondary metabolites are increased in co-culture. Co-culture is an important approach for discovering the active natural products from marine microorganisms associated with marine animals, and a new idea for the development of marine drugs.