Abstract: The mechanical model for a plant cell was built. The equilibrium equations of the model were determined by membrane theory. The mechanical responses were obtained by numerical simulation. The effects of osmosis properties of the cell wall on the mechanical response of the cell were discussed. The results show that the external force, principal tension of the cell wall, turgor and volume of the cell all decrease with increasing of the osmotic time. The stress relaxation occurs due to the migration of cell fluids out of the cell.