The oral administration ofEnterococusfaecium (EF1) to newborn suckling and weaned piglets along with their growth performances and intestinal microbiota was investigate in this study..Twenty-four newborn piglets were initially divided into 2 groups.The treatment or probiotics group receiving 2 ml of 10% sterilized skim milk by oral gavage was supplemented with viable Enterococcusfaecium EF1 (6×108 CFU/mL) at the first, the third and the fifth day after birth, while the control group was made of 2 ml of 10% sterilized skim milk without probiotic at the same time.Results showed that oral administration of Enterococcus faecium EF1 was associated with a remarkable increaseon the body weight of piglets for both suckling and weaning periods, by 30.73% (P<0.01) and 320.84%(P<0.01), and also decreased the diarrhea rate, by 43.21%(P<0.05) and 71.42%(P<0.05), respectively.In addition, 454-pyrosequencing analysis revealed that there was no significant difference in the intestinal microbial diversity of the suckling piglets between the two groups, nevertheless, when compared to the control group, the relative abundance of Firmicutes in the probiotics group substantially augmentedy, while the relative abundance of Proteobacteria, Bacteroidetes and Fusobacteria diminished.However, result indicated that oral administration ofEnterococusfaecium EF1 did not have any influence on the relative abundance of Firmicutes in weaned piglets rather than increasing the relative abundance of Bacteroidetes and decreasing the relative abundance of Proteobacteria.Furthermore, at level of Firmicutes phylum, the relative abundance of Lactobacillales in theprobiotic group increased significantly.These findings suggest that oral administration of E.faecium EF 1 to newborn piglets could improve the growth performance and intestinal microbiota of piglets for both suckling and weaning periods.