Based on information processing fluency theory,this study experimentally explores the influence mechanism of Internet celebrity library type and user-generated branded content appeals on user engagement behavior.It is found that users'online engagement behavior is more active when the warmth type of Internet celebrity library matches with the emotional appeal of user-generated brand content,and users'offline engagement behavior is more active when the competence type of Internet celebrity library matches with the functional appeal of user-generated content.Self-expression needs plays a mediating effect in the above influences,and self-construction has a moderating effect in the above influences.Based on this,the article proposes strategies for libraries to enhance their influence through the Internet celebrity phenomenon,which is to tap into their own resource advantages and clarify their distinctive positioning;establish an online digital platform and establish a brand image;seize digital sales opportunities to strength user stickiness;value user generated content and encourage user participation.