The current existing search model is mainly limited to syntaxbased keyword matching.By establishing domain ontology as the way of knowledge organization,this paper introduces a novel information search model based on domain ontology in semantic context.Then, document semantic annotation algorithm (DRSAA) and keyword semantic expansion algorithm (KSEA) are presented.These two algorithms are utilized to analyze semantics of document set and comprehend semantic relations of user keyword respectively,which realizes the objective of bidirectional semantic information search.At last,extensive experimental results demonstrate that the proposed information search method can overcome disadvantages of keywordbased search and improve the search results.