Abstract: The origin,extraction methods, biological properties and mechanism of essential oil and its regulation on rumen microbial fermentation were introduced. It was pointed out that essential oil was a kind of natural and green additive and it had good regulatory effects on the fermentation of rumen microbe. It was essential that different kinds of essential oils should be used in future research to study its regulatory effects on rumen microbial fermentation and its mechanism, so as to provide theoretical basis for producing new types of feed additives.