Traditional search engine is retrieval-oriented rather than user-oriented, in view of this weakness, the paper introduces the idea of personalized service to the enterprise search engine ranking. The user interest modeling technology which is the core of personalized service was researched in the paper. We apply the user interest model to query expansion and ranking and designed the personalized ranking method for the enterprise search engine. So the engine can display different result of the same retrieval for different users. We apply the personalized ranking to enterprise search engine in oilfield enterprise search and the tests show that, the research not only can effectively enhances the retrieval accuracy of the enterprise search engine and satisfies the user's personalized retrieval demand, but also has good adaptability.