The New Four Modernizations (NFM) synchronous development strategy proposed by the Chinese government is an important part of Chinese modernization and is of great significance in promoting the sustainable and high-quality development of the social economy. This paper aims to provide a framework for analyzing the dynamic evolution pattern of China’s NFM synchronous development. We expounded on the theoretical basis of China’s NFM synchronous development strategy. Then, the entropy method and convergence model were used to analyze the dynamic pattern and evolution trend of the NFM synchronous development in China. The findings are as follows: (1) In terms of the current situation of NFM development, China’s new urbanization and industrialization were in the middle stage, while informationization and agricultural modernization were in the initial stage of rapid development. (2) The level of China’s NFM synchronous development continued to improve, but the problem of unbalanced, uncoordinated, and unsynchronized development remained prominent. There were great differences in the development levels of China’s new urbanization, industrialization, informationization, and agricultural modernization, which showed that there was a problem of unbalanced and unsynchronized development within China’s NFM. On the other hand, the synchronous development level of NFM in the eastern, central, and western regions of China showed a spatial pattern of decline although the eastern region was clearly higher than the central and western regions; this revealed that the regional development of NFM in China was unbalanced and uncoordinated. (3) China’s NFM synchronous development has significant σ-convergence and β-convergence, indicating that backward regions are catching up and regional differences will gradually narrow in the future. This study is helpful in understanding the current situation as well as the dynamic pattern and future evolution trend of NFM synchronous development in emerging countries such as China.