城市非正规是快速发展中城市的普遍现象，“三旧”改造则是中国城市化后半期实现城市高质量发展的重要内容。针对当前学界对非正规用地进行“三旧”改造关注的不足，基于城市非正规性和尺度政治理论，选取东莞市“三旧”改造的典型案例，采用文献分析和深度访谈的质性研究方法，开展了其过程与机制研究。研究发现：东莞的“三旧”改造政策经历了政策申请、政策试点（含常态化）和政策修改三个阶段的尺度政治过程，伴随的是主要行动主体在此过程中“强势方”和“弱势方”角色的转变，以及改造地块“非正规—正规—非正规”状态的交互演变。“三旧”改造在实施过程中形成了各行动主体利益一致时顺利完成改造，以及利益不一致时地方政府重新修改政策，并对利益进行重新分配的两种路径，并以此循环，达到新的平衡的运行机制。研究有助于进一步丰富城市非正规性的理论进展，也为“三旧”改造和城市更新与治理提供一定的经验启示。

Urban informality is a common phenomenon in rapidly developing cities, and the "Three Olds" redevelopment is an important aspect of achieving high-quality urban development in the later stages of urbanization in China. Addressing the current lack of academic attention to the redevelopment of informal land use in the context of the "Three Olds" initiative, this paper, based on the theories of urban informality and scalar politics, selects a typical case of "Three Olds" redevelopment in Dongguan city. Using qualitative research methods such as document analysis and in-depth interviews, this study explores the processes and mechanisms involved. The research finds that Dongguan's "Three Olds" redevelopment policy has undergone a scalar political process consisting of three stages: policy application, policy piloting (including normalization), and policy revision. This process is accompanied by a shift in the roles of the main actors from "dominant" to "subordinate" and vice versa, as well as the interactive evolution of the land parcels from "informal-formal-informal" states. During the implementation of the "Three Olds" redevelopment, two pathways emerge: one where the interests of all actors align, leading to smooth redevelopment, and the other where, in cases of conflicting interests, local governments revise policies and redistribute benefits. These pathways cycle to achieve a new equilibrium. The study contributes to further enriching the theoretical understanding of urban informality and provides practical insights for the "Three Olds" redevelopment and urban renewal and governance.