Six types of domain knowledge for data mining were summarized. A method of two-level
knowledge organization, that is a combination of index knowledge and domain knowledge, was
proposed. The former, as the knowledge catalog, codes the latter according to the characteristics of
knowledge. Domain knowledge base consists of rule, function, hierarchical knowledge and basic
information sub-bases. Syntax check for allkinds ofdomain knowledgewas discussed. Itwas pointed
out that conflict forms of domain rule included conclusion conflic,t confidence conflict and inclusion
conflict, and redundancy forms ofdomain rule included equivalence redundancy, inclusion redundancy
and condition redundancy. Check algorithmswere presented subsequently. A knowledge base system,
namedKB4DM (knowlege base for datamining), was implemented based on the research.