Abstract: Exploring the spatio-temporal disparities and the evolution of Chinese-Style Modernization (CSM) distribution in the Yangtze River Economic Belt (YREB) is instrumental in optimizing the significant productive forces layout within the region. This endeavor entails systematically guiding the transfer of capital, technology, and labor-intensive industries from the downstream to the midstream and upstream regions of the YREB, as well as from central urban areas to the hinterland. The objective of this study was to catalyze the formation of new growth poles in underdeveloped areas of the YREB, thereby fostering indigenous development vitality. Constructing an evaluation index system for CSM based on five major characteristics, I employed the entropy method to calculate the comprehensive evaluation index for CSM in the 11 provincial regions of the YREB from 2005 to 2021. Subsequently, leveraging spatial quantile technique, I simulated the gradient grouping of CSM. Utilizing the Dagum Gini coefficient method, I measured the relative disparities in the level of CSM. Additionally, based on the kernel density estimation method, I characterized the absolute disparities and dynamic evolutionary features of CSM level. The main findings were as follows: (1) From the eastern to the central, and then to the western regions, the level of CSM in the YREB exhibited a conspicuous gradient descent trend. (2) Overall, the level of CSM in the YREB was consistently on the rise, with the non-uniform development scenario tending to weaken. (3) Relative disparity values were relatively high within economically developed regions and between economically developed and underdeveloped regions, but the values exhibited a trend of reduction. Simultaneously, economically developed region in the YREB manifested a polarization phenomenon in the level of CSM, with absolute disparity showing a diminishing trend. This paper provided a crucial reference for the quantitative analysis of CSM and the measurement of relative and absolute disparities in CSM within and between the regions.