Abstract: Microbial preparation is a kind of biological agent that is able to regulate the composition and balance of microflora in digestive tract. It has been widely used in preparation of animal feed for optimizing the beneficial microflora and improving animal immunity. The development and application of microbial preparation not only changes the situation that the composition of animal feed lacks of biological component in China, but also reduces the cost of animal cultivation and promote the development of animal breeding industry. Here, we reviewed the application of microbial preparation in nutrition and feed of ruminants, analyzed the development status of microbial preparation at home and abroad, and put forward some application strategies on microbial preparation in nutrition and feed of ruminants.