在当代中国特殊的政治社会语境下，非政府组织由于其非国家属性，始终面临自身生存合法性的挑战。相比传统官方媒体的谨慎态度，蓬勃发展的社交媒体为中国的非政府组织提供了重要的替代性传播资源。本文以“大爱清尘”这一典型本土草根慈善非政府组织为个案研究的对象，试图考察中国草根非政府组织是如何策略性地调用社交媒体来促进自我组织管理、建构自身合法性以及推动行动主义目标的实现。研究发现，社交媒体在公益行动主义实践中的应用既展示了赋权的潜力，也存在自我约束的局限性。草根行动主义者采取了将社交媒体和传统大众媒体相结合以获取不同类型合法性来源的平衡的媒介策略，并在话语实践中采用了混合的表达策略，即总体上将目标议题非政治化，但在局部层面又在一定程度上进行了有限度的政治化表达，从而有意识地参与到意识形态和政策边界博弈的过程之中。

Non-Governmental Organizations, or NGOs, due to their non-state nature, always have to face the question of legitimacy of their existence in Chinese society under an authoritarian state. Whereas traditional party-state media have adopted a vigilant approach to NGOs, the booming Chinese social media have provided alternative communication platforms for NGOs in China. Based on a case study of Love Save Pneumoconiosis (LSP), a domestic originated grassroots charity NGO, this research aims to illustrate how Chinese grassroots NGOs have strategically deployed social media to manage self-organization, construct self-legitimacy, and promote advocacy goals. Both empowering potentials and self-limiting practices of social media usage in NGO activism are identified. A balanced and complementary media strategy as well as hybridized narrative strategies which depoliticize the advocated issue in general but tactfully politicize it at partial levels are adopted to ensure self-legitimacy and maximize communicative effectiveness.