Urban public space, as a core component of the urban, is an important carrier for the residents' quality of life, social interaction and cultural inheritance. With the deepening of urbanization, urban public space is facing unprecedented challenges, including aging space, single function, environmental degradation, and mismatch with residents' needs, etc. This paper comprehensively discusses the application of digital twin technology in urban public space renewal, and systematically analyzes its core role in enhancing the function of public space, promoting the optimization of resource allocation, and reinforcing the ability of predictive analysis from the theoretical framework to specific countermeasures. Through the introduction of genetic algorithm and ARIMA model, the technical support of complex resource allocation and future trend prediction is shown; and the successful application and significant effect of digital twin technology in actual projects are demonstrated with the examples of The Bund in Shanghai and Marina Bay Gardens in Singapore. In addition, a detailed assessment of data security, technical compatibility, public participation and cost-effectiveness is made, and targeted countermeasures and recommendations are proposed.