Firstly, a method of intuitionistic fuzzy sets based truth ?? cut sets is presented. Based on this cut sets method, an
intuitionistic fuzzy set based fuzzy information system ISI(intuitionistic fuzzy information system) is proposed. The system
model and the objects satisfiability at a given threshold are analyzed in detail. It is proved that ISI are the generalization of
traditional information systems. Finally, an ISI based formal concept analysis theory is proposed, and the application of ISI
in the knowledge discovery and knowledge reasoning is discussed. Theory analysis and examples show the correction and
effectiveness of ISI in term of real world description and fuzzy reasoning.