The purpose of this study is to integrate the procedure of Formal Concept Analysis (FCA) in an automatic way for constructing an ontology based on the vocabulary of ”Information Warfare”. Besides, this study uses the methods of ontology and association rule to design a retrieval prototype of the PRC military news so as to analyze the similarity of semantic concepts; and further to recommend expanded keywords for users. The outcome of this research examines that using an automated method to build ontology has a higher efficiency, and the prototype of Query Expansion system has also improved the effectiveness of information retrieval. Besides, ”Information Warfare” ontology can also be used as a reference to the future research.