<p>Common prosperity is a pivotal component of China's modernization strategy, yet a uniform quantitative standard for this concept has not been established. The development of a practical and quantifiable index is crucial for advancing the goal of common prosperity. This study employs panel data from 309 prefecture-level cities and above, covering the years 2014 to 2020, to explore the dynamics of common prosperity at the urban level. By employing an equal-weight common prosperity function, the research extends measurement techniques and incorporates a range of methods to analyze the distribution dynamics, interval differences, structural disparities, and convergence characteristics of common prosperity. The results show that common prosperity levels in urban areas have consistently increased, with particularly notable growth rates in the western region. Despite this progress, the spatial distribution maintains a stepped structure from east to west. The common prosperity index displays a more dispersed spatial pattern, with a pronounced northeast-southwest orientation. The study also identifies significant positive agglomeration effects, characterized by high-high and low-low clustering, accompanied by spatial spillover. There is evidence of significant convergence in the levels of common prosperity, indicating a narrowing gap between cities. Further analysis indicates that most cities tend to inhibit the convergence of common prosperity, and disparities between the three major regions and provinces remain key factors influencing the overall level of common prosperity. These findings underscore the complexity of achieving common prosperity and highlight the need for targeted regional policies to address these disparities effectively.</p>