Abstract: The attribute reduct algorithm CARRDG，which can efficiently compute total attribute reducts for large scale information system，has been proposed recently.Although it has rigorous theoretical foundation，further improvement may be possible，especially in the implementation level.In addition to the existed three heuristic deep-first searching principles（Member Executive Principle MEP，Friend Persuade Principle FPP，Stranger Enter Principle SEP） based on reduct discernibility graph，a mew heuristic searching principle——Blocking Layer Block Principle（BLBP） has been proposed in this paper to improve the searching efficiency.Since the reasonable data structures have been developed，BLBP will not increase the implementing complexity of the algorithm.In contrast，the experimental results by using UCI data show that BLBP exceeds MEP and FPP in trimming efficiency for some large information systems.