Website users’ mental models can greatly affect their behaviors when looking for information. If their mental models closely resemble the interface designer’s representation model, the users will have an easier time to accomplish their search task. So it is beneficial to quantify the similarity and differences between users’ mental models and the representation model of website designers using the pathfinder network approach. With data gathered from undergraduate seniors (as users) and designers of the website at www.amazon.cn, this research presents the measurement and visualization method of website users’ mental models based on pathfinder network in their information seeking process, followed by a discussion on similarity calculation between the users’ mental models and the designers’ mental model, and corresponding system that implements pathfinder network methods also developed.