Abstract: To realize an optimal control of a class of DES (Discrete-Event-System), this paper analyses the causes that affect the operation efficiency, presents a target for optimal control, and, according to the combination of local optimal and global optimal control, suggests an effective suboptimal control method. This method is analysed and proved to be not complex. The computer simulations indicate that the closed-loop DES has a process from dynamic to steady state. However, only when the producing process is programmable, the whole efficiency can be better as the process continues.