本文从媒介行动主义视角来审视纪录片《穹顶之下》及近年在中国勃兴的另类传播行动实践。本文认为，当下中国的集体行动中开始呈现媒介行动主义趋向；新社会运动理论和资源动员理论是其理论背景。中国的媒介行动主要采取监督、溢散、近用、另类媒体等行动策略，其工具型、短期性、个人化、实践取向与西方媒介行动主义的政治性、长期性、公共性、理论主导有一定差别。中国的媒介行动主义在推进公共表达、决策民主、权益维护与增强国家传播软实力等方面具有重要价值，应纳入中国发展传播学的研究视野并给予理论和实践回应。

This paper examines the documentary under the dome and other alternative communication practices through the lens of media activism. The author argues that some media activism trends are emerging in the collective actions in present china, whose theoretical bases are new social movement theory and sources mobilization theory. The Chinese media activism mainly takes the tactics of supervising, spilling over, accessing and alternative media, and has different characteristics of instrumental, temporary, individual and practical from the political, persistent, public, and theoretical of the west. The media activism in China shows important values in the field of promoting public expressing, democratic decision making, civil rights protecting and enhancing soft power of international communication of China, and deserving theoretical and practical response from the lens of development communication.