The invention provides a Microblog-based user age classification method and a Microblog-based user age classification system. The Microblog-based user age classification method includes the following steps that a user to be tested is obtained, and the user to be tested is a Microblog user who does not provide age information; a Microblog text of the user to be tested is obtained; the Microblog text of the user to be tested is segmented, so that text phrases to be tested are obtained, and according to a preset rule, the text phrases to be tested are converted, so that a feature vector to be tested is obtained; the feature vector to be tested is adopted as an input value of a pre-created maximum entropy classifier, so that a testing result is obtained; the testing result is utilized to determine the user age type of the user to be tested. By obtaining the Microblog text of the user to be tested, after carrying out related processing on the Microblog text, the application utilizes the maximum entropy classifier to obtain the testing result, and determines the user age type of the user to be tested according to the testing result, consequently, utilizing the maximum entropy classifier to carry out testing with the Microblog text published by the user to be tested as a basis can ensure that the determined user age type of the user to be tested is more accurate, and moreover, universality can be realized.