在我国，伴随新媒体技术的发展，社交媒体为普通公众的信息获取和意见表达提供了便捷通道。在这一背景下，网络问责成为传统行政问责的重要补充，但也为公共谣言的滋生提供了温床。在问责情境下，政府须公开应对公共谣言，而如何有效应对谣言危机成为公共管理者在新媒体传播环境下所必须正视的重要议题。本文就政府的公共谣言应对过程中媒介信息对网络舆情的作用机制进行研究，以探索政府解除公共谣言危机的有效路径。在已有研究的基础上，本文就影响公众对辟谣信息接受程度的相关变量进行整合。政府在公共谣言应对中并非只扮演“辟谣者”的单一角色，其对事件的处置同样会影响谣言应对效果。此外，官民矛盾是指向政府的公共谣言的深层诱因，谣言激化官民矛盾的程度不同，谣言应对所获效果也可能存在差异。就此，本文提出囊括造谣者、谣言本身、辟谣者、辟谣信息、谣言处置相关变量在内的谣言应对效果分析框架。以政府机构/官员出面应对、引发公众广泛关注的公共谣言事件作为研究对象，以定性比较分析和案例分析对本文提出的理论框架进行检验。研究以新浪微博平台作为研究对象，对主流媒体于2017-2019年发布的针对公共谣言事件政府辟谣的热门微博及其引发的热门网民评论逐条进行文本分析，并对相关数据进行定性比较分析。研究结果给出政府单轮辟谣时有效辟谣所需的条件组合，并指出我国网民的信息处理路线为中心路线，即基于全面信息得出立场。第二阶段的实证研究采用单案例和比较案例研究方法，选取政府应对过程较为复杂、受到系列报道或连续报道的公共谣言事件，就媒介信息的作用机制进行进一步检验。对贵州福利院儿童遭强奸事件、12岁留守女童多次遭强奸事件、红黄蓝幼儿园猥亵幼童事件、成都七中实验学校食堂事件进行四项单案例研究，并进一步对四个案例进行比较案例研究。实证检验了政府应对过程中各要素动态变化对相关网络舆情的作用情况，以分析事实性信息和意见性信息对网络舆情的作用机制。主要的研究发现有：1. 我国公众的信息处理路线为理性的中心路线。2.事实性信息与意见性信息均能够作用于网络舆情。媒介信息通过事件模糊程度的传导机制影响公众对辟谣信息的接受程度。3. 政府谣言应对质量不佳会抑制公众对辟谣信息的接受。公众会基于相关媒介信息，就政府应对的辟谣信息反常度、政府处置反常度进行评估，以此决定是否接受辟谣信息。

With the development of New Media, social media users are allowed to generate content and have easy access to information from various sources. In such a circumstance, Network Accountability is becoming a supplement to Administrative Accountability System, however, it also creates a breeding ground for rumors about government/officials. The Accountability System requires the government to give response to rumors, and that makes “how can the government cope effectively with rumors?” an important public management research issue in the new media environment. Therefore, this thesis works on the main influences on the shift of public opinion on rumor incident and the mechanism of public opinion shift.On the basis of the existing researches, the known variables which can influence the public’s acceptance of rumor rebuttals are integrated. This paper suggests that the government does not only deny or refute the rumors, but also does investigation and deals with those who are responsible for the rumor, the way the government handles the incident may affect ho w the public see the rumor rebuttal. This study therefore raises the mechanism of rumor monger, rumor, rumor refuter, rumor denial and government disposal on the public’s acceptance of rumor rebuttal. Text Analysis, Qualitative Comparative Analysis and Comparative Case Analysis are applied to examine the proposed theoretical model. This paper takes Sina Microblog as the research object, examines the rumor denial cases posted by mainstream media in the recent three years by performing text analysis on the microblogs and the comments from Sina Microblog users. The Qualitative Comparative Analysis examines the influence factors of the public’s acceptance of rumor denial, the findings identifies the combinations of conditions that explain people’s acceptance of rumor denial in the rumors which may foment social tension and the ones which may not. In addition, Comparative Case Analysis are performed by conducting in-depth case study on Guizhou Welfare center sexual abuse event, 12-year-old left-behind girl sexual assault event, Chengdu NO.7 High School Development School canteen event and RYB Kindergarten indecency event. By taking Process Tracing method, the relevant microblogs and the comments from Sina Microblog users are examined. This empirical test shows how the factors influence the public’s standpoint in the whole rumor disposal process.The main findings are: 1. The public take the central route to process information. An effective rumor rebuttal requires a combination of conditions on rumor monger, rumor, rumor refuter, rumor denial and government disposal. 2. Both factual information and influential information can make a influence on the public. Media information acts on the public’s acceptance of the government’s rumor rebuttals via the transmission mechanism of information ambiguity. 3. The abnormality of the event information and the government’s disposal regulates the public’s acceptance of rumor rebuttal.