Keratoconus is a bilateral asymmetric corneal dilatation disease characterized by localized thinning and increased curvature of cornea. The alteration of the mechanical properties occurs earlier than morphological change owing to corneal structure destruction in the early stage of keratoconus. Therefore, the corneal biomechanics is especially important for early keratoconus screening. In this paper, we reviewed corneal biomechanical behaviors in vivo and corneal mechanical properties in vitro during the development of keratoconus and corneal cross-linking treatment. The role of finite element methods and animal models were also analyzed in the research of keratoconus disease. This review provides a reference for the diagnosis and treatment of keratoconus in clinic.