In 2012，the additives event of red bull became one of the top ten public opinion events on food safety，which exposed the weakness of food supervisor in China. Media Agenda played an important role on the additives event. Take the additives event of Red Bull as example，this paper found that there were 5 main issues，such as the additives problem，the mechanism to deal with any type of PR in crisis and so on. It suggested some reasons lead to the issues transformation in additives event of Red Bull，such as the sensitivity of the event，mass media agenda setting，the improvement of citizen consciousness and the fission spread of public issues.