Hybridization has been reported could significantly promote growth in sheep and rumen microbiota is associated with animal growth and health. Although it has been commonly accepted that diet plays the main role in shaping the gastrointestinal microbiota, more and more recently evidence revealed that host genetics is also an important factor in determining the composition of gut microbiota. However, there have been limited research on the host genetics effects on the growth performance in hybridization sheep previously. Therefore, in this project, we hypothesized that rumen microbiota composition and function of sheep are affected by host genetic effects, and then affected growth performance. We assessed the rumen microbiota and metabolites profiles of hybridization sheep raised under the same farm environment, aimed to elucidate underlying molecular mechanisms, and thus, provide a theoretical and practical basis for improving the growth performance of hybridization sheep and new breeds breeding.