In the contemporary city, where numerous challenges such as global climate change are increasingly prevalent, the strategic allocation of urban green spaces emerges as a crucial mechanism to bolster urban resilience. Furthermore, the equitable distribution of these green spaces is paramount for safeguarding the health and well-being of urban residents. However, the pursuit of such balance is notably arduous within the context of high-density urban areas, where spatial constraints impose significant limitations on the development and distribution of green spaces. This paper proposes to use Informal Green Spaces (IGS) as an important potential space to improve the equity of urban green spaces. To address the issue of spatial limitations, the paper suggests that IGS should be integrated into the existing urban green space system through a variety of innovative and contextually sensitive strategies. By doing so, it aims to alleviate the problem of unequal distribution of green resources, which is a common issue in densely populated urban environments. To this end, the study takes the Gulou District, located within the old industrial area of Xuzhou City, as a case study. Utilizing the Gaussian two-step moving search method coupled with the Gini coefficient method, the paper conducts a quantitative assessment of the current equity levels of urban green spaces within the district. Moreover, the research establishes a temporal evaluation framework for the renewal of IGS, which serves to further promote the equity of green spaces over time. The results show that: (1) The green spaces in the Gulou District of Xuzhou City are in a severely unequal state, with a Gini coefficient of 0.79. (2) 78.46% (51 plots) of the IGS have varying degrees of potential to improve the equity of green spaces in Gulou District, but the proportions of IGS with very high and high potential are only 1.54% and 4.62%, respectively, with limited potential for upgrading. (3) The renewal plan for the spatial distribution of green spaces in Gulou District includes the proposed addition of 10 comprehensive parks, 8 community parks, and 3 gardens. The comprehensive guide provided by the study's findings is of significant utility for the renewal planning of green spaces within high-density urban built-up areas. It can inform and guide the strategic development of urban green spaces in a manner that is cognizant of the need for equity and sustainability. Moreover, the study's insights provide a substantial basis for decision-making processes in the context of brownfield redevelopment and the repurposing of idle land functions. By doing so, the research contributes to the broader objectives of sustainable development within urban communities.