Piglet diarrhea stands as the primary cause of piglet mortality, inflicting substantial economic losses to pig farmers. Porcine rotavirus (PoRV), a member of the Reoviridae family, bears responsibility for instigating diarrhea and severe dehydration, culminating in piglet fatalities. Portulaca oleracea L. (POL), a Chinese medicinal herb commonly utilized for its antiviral properties and effectiveness in treating diarrhea, holds promise for mitigating these effects. Nevertheless, the in vivo antiviral effect of Portulaca oleracea L. polysaccharide (POL-P), a key component of POL, on PoRV infection remains obscure. This study aimed to investigate the antiviral effects of POL-P on PoRV in piglets and its impact on their intestinal flora. Studies have demonstrated that oral POL-P improves growth in both lactating mice and PoRV-infected piglets, while reducing diarrhea and mortality. It also helps to reduce intestinal damage and lower viral mRNA levels in the jejunum and ileum. Additionally, POL-P improves blood tests in piglets, boosting levels of IFN-α and IL-10, and lowering tumor necrosis factor-α and IL-6. Analysis of the intestinal flora in PoRV-infected piglets showed reduced levels of Bacteroides (18.39 %) and increased levels of Firmicutes (39.81 %), Proteobacteria (33.46 %), and Verrucomicrobia (7.42 %). After POL-P treatment, Bacteroides increased to 28.31 %, while Firmicutes, Proteobacteria, and Verrucomicrobia decreased to 34.93 %, 25.52 %, and 2.53 %, respectively. At the genus level, POL-P treatment reduced the abundance of Klebsiella, Ackermannia, and Streptococcus. In conclusion, POL-P helps reduce inflammation and intestinal damage caused by PoRV infection, prevents viral colonization, restores gut flora balance, improves piglet growth, and reduces diarrhea and mortality.