For the extremely frequent changes in e-commerce users’ interest, a linear-attenuation based user profile is proposed. The registered information and browsing behaviors are used to set up the initial chain user preference list. The User Profile is made up of all users’ chain preference list. User ratings decrease at a fixed time interval until the rating has been eliminated to zero. User preference value is probably updated by a new rating in the course of attenuation. The efficiency of user profile is proved by the experiment.