Through examples it proves that the optimal method of the combinational logic based on the rough set is both feasible and effective.

In this paper,we have not only expressed the consideration of design about un-iversion variable input of combinational logic cricuit,but also given the method and steps by designing same special example.

For the simple and clear controls,have designed a method as follows:setting up some functions of combinational logic,simplifying expressions of them,translating the expressions into PDL and programing.

An algorithm of combinatory logic optimization based on rough set;

Design with Mid-scale Integrate Circuit to Improve the Combined Logical Circuit in Engineering;

In such condition, the application of non-linear editing system to edit VCD programs would waste much time while the application of traditional linear edition is the most effective method, in which combined edition and inserting edition are two common ways.