Abstract: Aiming at the computational problem of rough sets,a measure and computational approach to studying rough set theory based on matrixes is proposed.The approach acquires a measure set denoted in the form of matrixes and the matrix computation of relationships between set and equivalent class by introducing some basic concepts such as class matrix operator,relation matrix operator,set matrix,and with the help of the level cut matrix of product matrixes.The properties of the method are also disscussed.The steps of attributes reduction about the approach applied to a variable precision rough set model are presented.The correctness and effectiveness of the new approach are shown with an example.