Lipases are among the most applied biocatalysts in organic synthesis to catalyze the kinetic resolution of a wide range of racemic substrates to yield optically pure compounds. Due to the rapidly increased demands for optically pure compounds, deep understanding of the molecular basis for lipase stereoselectivity and how to obtain lipases with excellent asymmetric selectivity have become one of primary research goals in this field. This review is focused on the molecular factors that have impacts on the stereoselectivity of lipases including the steric complementarity between the lipase topological structure and its substrate, the regional structural flexibility, the hydrogen bonds between the residues around the catalytic site and the tetrahedral intermediates, and the electrostatic interactions between surface residues. Moreover, the synergistic effects of these structural factors on the catalytic properties including stereoselectivity, activity, and stability are also discussed.