Abstract: Microecological agents as a kind of green feed additive model, has some functions of regulating animal intestinal micro ecological balance, promoting animal growth, improving feed conversion rate, improving animal immunity etc., and has wide application prospect. The types and mechanism of action of microecological agents were reviewed in this paper, and the application of microecological agents in enhancing animal′s immunity, improving feed conversion rate, reducing stress, purifying air and improving water quality in the zoo were also discussed, meanwhile problems and solution methods of microecological agents applying in wild animals in the zoo were pointed out.