Molodtsov initiated the concept of soft set theory, which can be used as a generic mathematical tool for dealing with uncertainty. Description Logics (DLs) are a family of knowledge representation languages which can be used to represent the terminological knowledge of an application domain in a structured and formally well-understood way. The current research progress and the existing problems of soft set theory are analyzed. In this paper we extend soft sets with DLs, i.e., present an extended soft set theory by using the concepts of DLs to act as the parameters of soft sets. We define some operations for the extended soft sets. Moreover, we prove that certain De Morgan’s laws hold in the extended soft set theory with respect to these operations.