To study accommodation mechanism with numerical simulation. · METHODS: A simulation model was constructed to study the mechanism of accommodation based on the experimental data derived from published resources. The displacement and pressure were applied on the model to study the deformation of lens during accommodating. · RESULTS: The simulation showed that, as the eye was accommodating, the thickness of the lens increased linearly, and the lens diameter decreased linearly. The optical power of the lens increased as the accommodation increased. This result was accord with the public facts in accommodation. Furthermore, the pressure was found to have a great influence on the shape of the lens and the optical power. The lens became thinner and flatter as the pressure increased and the pressure caused a remarkable increase of lens' optical power. · CONCLUSION: The outcome of this paper is consistent with the Helmholtz's hypothesis on accommodation to some extent. The analytical model presented in this paper can be used in the theoretical study of the accommodation mechanism of the human lens.