In this paper, we will introduce a hybrid knowledge system SHOIQD to integrate the description logic SHOIQ and nonmonotonic rules preserving decidability. We first define the syntax of the integrated knowledge base and then introduce it’s semantic based on well founded semantic. Next, we develop a new algorithm to answer queries over the knowledge base. Our algorithm is combination of SLS-derivation procedure which is the reasoning algorithm for nonmonotonic rules and the Tableaux reasoning algorithm used in the description logic. Thus, the existing ontology reasoners and rule reasoners could be re-used when implementing our algorithm.