Abstract: Using temperature optimization process and embedded atom method (EAM), the equilibrium melting point of Cu was calculated under the constant-temperature and pressure molecular dynamics. The influence of time step on the calculated results was also studied. The simulation shows that the shorter the time step is, the smaller the difference between the calculated melting point and the experimental is. When the time step is below 0.05 fs, the decreasing of time step has no effect on the calculated melting point in the range of calculation precision.