Abstract: The machine-made trait of search engines brings great trouble to people when they retrieve information. Therefore, the technology of user profile is introduced to solve the problem which makes search engine fit for people' demands of individuation and intelligence better. A modeling method of user profile based on ontology is advanced. And the innovation of this paper is to do modeling with a method of combining tree graphics and spatial graphics together, to set up ontology nodes in spatial graphics and to introduce the theory of interval valued fuzzy sets. In addition, the paper explains the method in theory, brings forward some correlative definitions and formulae, and designs an algorithm of founding and updating nodes based on ontology (LW-FUNO). The modeling method is helpful in overcoming the deficiencies of traditional modeling methods and is in favor of user profile's foundation, use and perfection. Finally, a well-ordered implement is used to prove correctness of the algorithm strictly, and then, time complexity of the algorithm, which is T(n)=o(n\+2), is analyzed. It is proved theoretically that the algorithm has the traits of correctness, validity and low time complexity. It is considered that the work in this paper is a useful attempt at the research of user profile.