Rotavirus (RV) epidemiological surveys with molecular analysis of various strains are required for gastroenteritis control and prevention. The lamb rotavirus strain NT, isolated from a diarrhea lamb in China, is considered as a promising vaccine strain. The whole genome of the lamb-NT strain was determined by sequence analysis. Sequence identity and phylogenetic analysis defined the lamb-NT strain as group A, genotype G10P[15]/NSP4[A]/SG1 strain. Comparative genomic analysis of the lamb-NT strain and 17 reference strains reveals that gene reassortments between rotaviruses circulating in different species occurred. Alignment of protein sequences of the genes shows some variations in the important functional regions of VP3 and VP4. These variations are related to host range restriction, virulence, and other potential characters of rotaviruses. Besides, this study also makes a significant foundation for the study of genetic classification, epidemiology, and antigenic diversity of rotaviruses on the molecular level.