MicroRNA（miRNA）is a class of endogenous non-coding small RNA molecules that are between 20 and 24 bases, it widely exists in animals，plants and other livings and binds to the target gene-specific target gene mRNA to cause degradating or inhibiting protein translation. So it has a wide range of biological functions. The formation and development of embryo takes an important position on animal reproduction, evolution. Recent studies showed that miRNA had effect on animal reproduction, embryonic development. To explain the molecular mechanism of its regulation, this paper reviewed the research of miRNA in animal embryo formation and development.