Abstract: In order to deal with attributes reduction, one of the major problems in rough set theory, an attributes reduction algorithm was proposed based on scan vector, and a new conception of discernible vector was defined by which the information table can be transformed into discernible vector sets. Depending on the structural feature of the discernible vector, a plus rule for the discernible vector sets was defined, and a scan vector with concise structure but representing the information table can be obtained through scanning the discernible vector just one time. The item of attribute frequency in the scan vector was taken as heuristic information to improve the efficiency of attributes reduction. An illustration and experimental results indicate that the method proposed is much more effective.