Base on Tersoff and Lernnard-Jones potentials, molecular dynamics simulation of nanoindentation experiment on single layer rectangular graphene film is carried out. A typical force-displacement curve is obtained and the effects of various factors including indenter radius, velocities as well as boundary conditions on the simulation results are discussed. The Young's modulus and the strength of the graphene are measured as 1 terepascals and 90 gigapascals, respectively.