Since the 1990s when blog was born,the blog has been developed into news transmission carriers from individual diary.Because of the characteristics of blog such as proruption,participation, openness and so on,in news transmission,traditional media are facing challenge.However,because of the defects of blog such as low public belief and instruction,the blog can not replace traditional media and news organizations.What the blog can do is to make valuable complement to traditional media and to promote traditional media to make reform.