2019年下半年的香港社会事件让城市陷入混乱，也让东方之珠成为国际新闻焦点。本文在这个事件背景下关心两个问题：到底发生什么事？为何事情会发展到如此地步？有关这个事件，有媒体称之为“反修例运动”、也有另一种声音强调这是“黑(衣)暴(力)风波”，同一事件却有不同表述，折射出政治传播的“无用之用”——可以动员社会群众采取具体行为，也影响不同的新闻媒体为同一事件留下了不一样的纪录，如果我们相信“新闻是历史的初稿”。到底事件为何会有这样的发展轨迹，也是众说纷纭。一个以修改法律，惩戒凶手为动机的修订法律行为，却在政治传播的推动下，快速“变身”成为一连串政治诉求的大规模社会运动。政治传播的“无用之用”在香港特殊的公共治理环境中，迸发出多数人意想不到的巨大动员力量。本文把握“政治传播”与“社会动员”两个关键词展开研究，希望找出政治传播如何产生政治动员效果的机制。本文在文献的支持下提出情绪、利益、价值与网络四种动员机制，并透过2019年香港社会运动背景来检验。本文透过德尔菲法独立访谈了10位不同背景的事件参与者，用他们的经历交叉印证，再配合文本分析法来找出新闻媒体在事件中的新闻关键词使用趋势，两者结合分析。结果发现政治传播透过内容来对受众产生情绪、利益、价值方面的动员，而这种动员功能在网络传播科技发挥“放大镜”与“加速器”功能之后，可以快速放大动员效果，成为2019香港社会事件的催化剂。研究还发现，香港独特的公共治理环境给政治传播提供了特殊的舆论环境，对推动及结束社会运动都起到了助力的作用。本文也同时分析了特区政府在2019社会事件中的政治传播，总结出不重视、不管理、不创新、不了解的四个短板，并根据采访意见提出四项建议：“长期重视，培养人才”、“长期规划，动态调整”、“鼓励创新，尊重多元”、“了解受众，提高技巧”。虽然特区在中央支持下已经“由乱及治”，街头暴力已经消失，但意识形态对立等隐形抗争仍未消失，如何准确掌控民意仍是特区政府无法回避的挑战。

In the second half of 2019, a social issue pushed Hong Kong in a huge chaos and immersed the global media focus. This article is concerned with two questions in such a background：What’s happened here? How it turns in an unexpected way.There are several names about the same issue, some people call it “Anti-extradition law movement” and some people insist this is a “black terrors”. Different expressions reflecting the unique power of political communication, which is able to mobilize the public to take action in real life, but also influence all the media to leave different records for the same event. When we ask why the social event finally turns into a turmoil, everyone have his own opinion, and this article believes political communication plays a key role to push the issue into a huge chaos.This paper attempts to find out the mechanism to explain how political communication mobilizes the public. With the support of literature, this paper proposes four mobilization mechanisms, namely Emotion, Interest, Value and Online, and examines them through the context of Hong Kong social movements in 2019.In this paper, 10 event participants with different backgrounds were interviewed independently by The Delphi method, their experiences were cross-verified, and text analysis was combined to find out the trend of news keywords used by news media in events. The results show that political communication can mobilize the audience in terms of emotions, interests and values through content, and this mobilization function can quickly amplify the mobilization effect after the online communication technology plays the function of "magnifying glass" and "accelerator", and become the catalyst of social events in Hong Kong in 2019. The study also found that Hong Kong‘s unique public governance environment provided a special public opinion environment for political communication, which played a role in promoting and ending social movements.This paper also analyzes the political communication of the Hong Kong Special administrative Region government in 2019 social events, and summarizes four weaknesses. This paper provides four suggestions based on the interview opinions.