Abstract: An improved Metropolis approach is proposed especially to solve the equilibrium problem of a discrete-state system, used to deal with the Ising model and proven to be well consistent with the traditional Metropolis method. But it's more efficient as it reduces 25 percent of the simulating time. Especially for the Ising model, the Master equation is generalized in the simulation. This kind of Master equation of critical kinetics and its' transient phenomena can effectively be studied by using the modified Metropolis method presented here.