中文摘要：

面对日益频发的突发事件如果处理不当极易引发危机事件，而微博传播以其独特的技术优势在突发事件的风险沟通中频频发力，备受瞩目。在复杂的“危”为“机”转化过程中，网民使用微博的心理有哪些特征，如何影响传播效果？本文以2011年突发事件上海地铁9·27事故为例，试图回答本身已经占据处理先机的突发事件为何“虎头蛇尾”导致先“机”后“危”的结果，并且以此为例着重从认知失调、引爆效果等理论阐释网民的认知心理特征进而展开尝试性探究，希望对突发事件的风险沟通具有启示意义。

英文摘要：

It could easily be led to a crisis event if not handled properly in the face of frequent inci- dents. However, micro-blog has played an important role in the risk communication with its unique techni- cal advantages and thus got more and more attention. What are the traits of the Netizens＇ mind and how to affect the communication effect in the transformation process from ＂crisis＂ to ＂opportunity＂？ With the case study of Shanghai Subway Crash on 27th September, this paper will focus on the cognitive psychological and priming theory to explain the transformation process from ＂opportunity＂ to ＂crisis＂. Hopefully, it will bring good effect on risk communication.