The invention relates to a user identity identification method and system. Through basic information, comprising user ID, user name, Email, telephone number, computer IP and the like, formed by user registration, and carrying out extraction on website user behavior data, and by combining information, such as user ID, user name, Email, telephone number, Cookie, computer IP and the like, related in the behavior data, a user information relevance relationship between the two is established and an unique identification identity is given, unified identity identification of users in a B2B website at present can be carried out, identity characteristic relation is established, old and new users can be identified, and user behaviors can be effectively tracked, and thus a series of applications can be established for the users, and user experience is improved.