With the rapid development of internet, the question comes up as to who plays a stronger role in the creation of the public policy agenda: Internet media or the traditional media? This study takes the case of PM 2.5 information exposure as an example to explore how internet media and traditional media work together to promote the formation of public policy. By selecting samples of internet media, traditional media and policy agenda, and by way of the empirical analysis, we came to the conclusion that Internet media and the traditional media have the same agenda setting function; these two parties have their own advantages and influence each other and promote the establishment of the policy agenda together. This study supplements the theory of agenda setting.