Simulation of metal instability with the initial sine perturbation on the inside of the metal shell driven by cylindrical implosion is made, and the simulation results is in accordance with the experiments. By comparing with the simulation result without considering the strength of the metals, the analysis shows that the strength of unmelted metal has a strong inhibitory effect to the metal instability, and under certain loading conditions the growth rate of the perturbation will decrease with the increase of the perturbation mode number. After that, the laws of the metal instability under explosive-driven conditions are summarized. Before the implosion reflected wave arrives at the shell, RM instability plays a dominant role. After the implosion reflected wave is applied to the shell, RT instability is significantly enhanced, the effect combined with the strength of the perturbations shows a nonlinear evolution. Under both RM and RT instability condition, the strength of metal could cause the cutoff wavelength to exist in unmelted state.