The mechanical properties of silicene are investigated using ab initio calculation and molecular dynamics simulations with different empirical potentials. The simulation results show that the calculated Young's modulus of bulk silicene with EDIP model is consistent with the ab initio calculations. The chirality has a significant effect on the critical strain and stress of bulk silicene under uniaxial tension. In addition, the Young's modulus depends strongly on the chirality and size of the silicene nanoribbon due to the edge effects. The fracture process of a silicene nanoribbon is also studied.