Abstract: The relationship between decision tables and knowledge bases is described. An improved knowledge base verifying tool named KBV (Knowledge Base Verifier) is addressed, algorithms to check redundancy, conflicts,circularity and incompleteness of coverage are given. KBV works on the decision tables,it can verify knowledge base mixing specific and generic rules with frames, What is more,since logical relations between each subtables are considered in KBV, the verifying results obtained are at global level.