The nutrient content of abalone viscera is similar to that of muscle. It contains rich proteins and various biologically active substances. However, the abalone viscera are often abandoned when processing or during consumption of abalone. This is not only a great waste, but also causes pollution to the environment. In recent years, with the exploration and research of marine active substances, abalone viscera have also been studied and developed. Intestinal microorganisms are known as "external organs" of the host, they are directly involved in the host's nutrition, immunity, metabolism, and so on. They play important roles in maintaining the health of the host. A few studies have reported the in vitro and in vivo antioxidant activity of abalone polysaccharides and polypeptides; however, the effects of abalone active substances on the intestinal microorganism have not been previously reported. In this paper, the intestinal microbiota of tilapia and the influence of feeding abalone visceral crude polysaccharide (CAVP) on the intestinal microbiota were studied by PCR-DGGE and Illumina MiSeq sequencing. A total of 13 bacterial phyla were detected in the intestines of tilapia:Fusobacteria (77.84%) was the dominant phylum, Bacteroidetes (8.59%), Chlamydiae (6.18%), Proteobacteria (5.84%), and Actinobacteria (1.20%) were the subdominant phyla. Saccharibacteria, Firmicutes, Planctomycetes, Verrucomicrobia, TM6_Dependentiae, Cyanobacteria, Spirochaetae, Acidobacteria, and some unknown groups were also detected. At the genus level, (5.80%), (1.13%) were the subdominant genera. There was also an unknown genus of the family Porphyromonadaceae, accounting for 8.29%. In addition, , and some unknown genera were also detected. The addition of CAVP diet had an obvious influence on the intestinal microbiota of tilapia because the CAVP-treated samples and the control samples without CAVP clustered separately. After feeding CAVP, the abundance of Actinobacteria, Saccharibacteria, Verrucomicrobia, and TM6_Dependentiae decreased significantly ( and Neochlamydia, Acinetobacter, Mycobacterium, Alsobacter, Aquicella, Pseudomonas, Aeromonas, and Mycobacterium, Alsobacter, Aquicella, and P < 0.05). After feeding CAVP, the abundance of some pathogens, such as Mycobacterium abscessus, Acinetobabacter baumannii, Aeromonas sharmana, Tsukamurella tyrosinosolvens, and Mycobacterium abscessus and decreased significantly compared with that of the control (Cetobacterium, increased. This study investigated the effects of CAVP on the host with regard to intestinal microbes; it provides insight into the efficient evaluation of marine active substances, and also lays a theoretical foundation for the development and utilization of bioactive substances and the development of prebiotics from abalone viscera. In addition, this study is of importance in recycling abalone viscera and reducing environmental pollution.