Objective This study aimed to investigate the effects of P.odoratum extract on lactase activity and microflora diversity in mice with bacterial dysbacteriosis.Methods SPF male BALB/c mice were randomized into 4 groups:control,model,P.odoratum extract low dose(1.56 g·kg-1·d-1)and high dose(3.12 g·kg-1·d-1)treatment group.There were 8 mice in each group(5 in the blank group).In addition to the control group,after 7 days of intragastric administration of mixed antibiotics,the administration groups were given P.odoratum extract for 7 days,and the control group and the model group were given the same amount of sterile water.The changes of diarrhea,body weight and food intake of mice were recorded.The colon HE staining sections,ZO-1 protein,IL-6 expression,and serum LPS concentration were detected.Feces were collected for lactase activity and microbial diversity determination with 16S rRNA high-throughput sequencing technology.Results After 7 days of antibiotic intervention,compared with the control group,the mice in the model group had soft stool,weight loss,reduced food intake,and significantly reduced intestinal flora diversity.At the 14th day,in the model group,ulceration accompanied by slight interstitial congestion and edema was seen in the colon,ZO-1 expression was significantly reduced,IL-6 expression was significantly increased,serum LPS was significantly increased,lactase activity was significantly reduced,and intestinal flora diversity was still lower compared with the control group.After 7 days of administration,compared with the model group,P.odoratum reduced the diarrhea rate of mice,promoted a recovery of body weight and food intake,downregulated pathological colon tissue damage,significantly increased ZO-1 protein expression,and reduced colon factor IL-6 and serum LPS concentration.In addition,P.odoratum can significantly up-regulate lactase activity and improve the community richness and diversity of dysbacteriosis mice.It is shown that three phyla(up-regulated Firmicutes,down-regulated Proteobacteria and Bacteroidetes)and seven genera(up-regulated Rikenellaceae_RC9_gut_group,Rikenella,Colidextribacter,norank_f__Lachnospiraceae,norank_f__Oscillospiraceae,and Lachnospiraceae_NK4A136_group,down-regulated Alloprevotella),the abundance of which was significantly correlated with body weight and lactase activity,serum LPS,and colon factor IL-6.Conclusion P.odoratum can alleviate the gut barrier injury and dysfunction caused by antibiotic induced dysbiosis,and its mechanism may be achieved by regulating microflora structure.