在后真相时代和社交媒体时代，关于三峡工程等重大工程存在着不同程度的公众风险认知偏差。某些围绕工程的公众风险认知偏差在未经有效防范的情况下，可能演变成蕴藏着严重后果的重大风险。本文将三峡工程公众风险认知偏差问题概括为五种基本类型；阐释了催生三峡工程公众风险认知偏差的重要原因，探讨了三峡工程公众风险认知偏差导致风险扩大的途径；并提出可通过建立积极信任，降低将风险认知偏差转化为现实风险的概率；开启多元对话，打破话语竞争的边界，建构有利于理性认知工程风险的良好传播生态。

In the post truth era and social media era,there are different degrees of public risk perception bias on major projects such asthe Three Gorges Project.Some public risk perception deviations around the project may evolve into major risks with seriousconsequences without effective prevention.In this paper,the public risk perception bias of the Three Gorges Project is divided intofive basic types,including risk expansion and risk fiction;This paper expounds the important reasons for the deviation of public riskperception of the Three Gorges Project,and probes into the ways for the expansion of risk society caused by the deviation of publicrisk perception of the Three Gorges Project;It also proposes the probability of rewarding the risk cognitive bias into reality byestablishing positive trust;open multiple dialogues,break the boundary of discourse competition,and build a good communicationecology conducive to rational cognition of engineering risks.