As a famous coastal tourist city in China, Sanya is facing the dual challenges of solid waste management and resource utilization while tourism is booming. To realize efficient solid waste management and innovative circular economy models, Sanya actively explores and practices the construction path of a “zero-waste city”. In this study, Pearson correlation analysis and material flow analysis were used to analyze the factors influencing the amount of municipal solid waste (MSW) generated in Sanya and the changes in the effectiveness of MSW treatment in Sanya before the construction of the “zero-waste city” (2018) and five years later (2023). The results of the study show that the construction of a “zero-waste city” in Sanya, through the implementation of a series of policy measures, including the strengthening of strategic planning and leadership, the upgrading of capacity building, and the promotion of nationwide action participation, has effectively promoted the efficient synergistic treatment of MSW, thereby realizing both environmental benefits and economic benefits.