In this paper a mathod for Solving the Optimal periodic control problem of discrete process by using Modilo-matrix is given and discussed. The mathod has a Strong point in the common use for the periodic control problem and less computations, It not only solves the specified periodic control problem, but also gives many better feasible Solutions for shorter periods while seeking the optimal solution. So it is of value to practical problems. Futhermore, the method is suitable to the implementation in parallel.