Optically active epoxides play important roles in pharmaceutical, agricultural and fine chemical syntheses. There are many chiral medications with pharmacodynamic activity in nature that can be synthesized by chiral epoxides. In recent years, researchers have developed a variety of biocatalysts for the asymmetric epoxidation of alkenes, which use oxygen or hydrogen peroxide as eco-friendly and low-cost oxidants, to provide better chemo-, regio- and stereoselectivity under moderate reaction conditions. In this paper, the advances, opportunities and challenges of the asymmetric epoxidation of unactive alkenes by biocatalyst are reviewed.