Abstract: By analyzing the weakness of optimistic Muitl-granulation rough set and pessimistic Muitl-granulation rough set, the Variable granulation rough set was proposed, the lower and the upper approximation were defined. Further- more, the properties of these three kinds of rough sets were discussed, and that the Variable granulation Rough Set is the generalization of Muitl-granulation rough set was proved. At last, some measures of those rough sets were defined, the relation of their measures was discussed.

Key words: Variable granulation rough set, Muitl-granulation rough set, Measure