〔Abstract〕 The 7-day-old SPF grade BALB/C suckling mice were gavaged withrotavirus(RV). At the same time, PBS negative control group and normal control group were set up, all mice were kept in SPF grade animal room to observe the diarrhea of suckling mice every day. On the 1 st, 2 nd, 3 rd, 4 th, 5 th, 6 th, 7 th, 8 th, 9 th and 10 th day after inoculation, respectively, 5 suckling mice were killed. The small intestine tissues of suckling mice were collected in sterile environment. The viral content was detected by qPCR method, RV load and the histopathological changes were observed by HE staining, and the activity of lactase was detected by commercial kit. RV was detected in the intestinal tissue of suckling mice on the first day of infection, and the relative content of RV was higher; severe diarrhea occurred in the first 3 d after infection; HE staining showed that the small intestine tissue of suckling mice was damaged, the villi of small intestine were shed off, and the length became shorter. The corresponding results of PBS negative control group and normal control group were negative; the lactase activity was lower than that of the PBS negative control group and normal control group. Therefore, the establishment of RV infected BALB/C suckling mice with secondary lactose intolerance animal model will provide a strong guarantee for studying the pathogenesis of lactose intolerance and drug intervention.