Along with the risk society，the “risk communication” is a information interaction and democratic dialogue process with multiplicity and complexity which is based on public perception.In order to achieve the effect of risk communication，the media，one of communication subjects，play important roles.Take “Killing doctors” event in the First Affiliated Hospital of Harbin Medical University as an example，the media have both positive roles in risk-informed，risk communication and risk oversight and negative roles in risk amplification.And there are three types of mechanisms for the media to play their roles：media absorbing，media comments and public opinion mobilization.