Abstract: Based on theory of the rough set, a new method of discretization of continuous attributes was presented. The traditional rough set theory can only deal with the discrete attributes in database. The concept of decision attribute support degree was proposed. Using feedback information from decision attribute support degree a new method of discretization of continuous attributes was proposed based on independent domain. The suggested method can improve the efficiency of knowledge reduction when the original decision table keeps stable. At the same time, the rule sets are simple with less segmental interval. The approach is encouraging and effective.