The invention discloses a privacy driven fine-granularity access control mechanism, comprising the following steps that privacy demands of users are defined according to granularity of different typesof information and types of the users accessing the information; after the users issue messages on a mobile online social application, the social application automatically analyzes content issued bythe users and finds sensitive words possibly leaking user privacy; and different degree of fuzzification is carried out on the sensitive words possibly leaking the user privacy according to the typesof the users accessing the content, and finally the messages watched by the different types of users are different messages consistent with content semantics originally issued by the users. Accordingto the access mechanism provided by the invention, the privacy leakage problem in the mobile online social applications can be effectively protected.