Abstract: As the core component of optical system, human lens accommodation is realized through the cooperation of ciliary, zonular and lens itself. Ciliary dragging the connected zonular leads to the lens deformation change which finally alters optical power. Through this process, light can focus on the retina and result in visual sense. Actually, lens accommodation is a mechanical process that affects visual quality and the prevalent eye degenerative diseases-presbyopia. This paper illustrates various lens accommodation theories as well as their developments, and also summarizes the mechanical properties of lens.