Abstract: Based on the perspective of the new development concept, an evaluation index system for high-quality agricultural development was constructed. The time-varying entropy method was used to measure the level of high-quality agricultural development in 30 provinces of China from 2003 to 2020, and the Dagum Gini coefficient was further used to empirically examine the spatial differences in high-quality agricultural development in China. The results indicated that: (1) During the sample period, the level of high-quality agricultural development in China showed an upward trend, showing a clear “point to surface” diffusion trend and a stepwise progression from east to west. (2) The high-quality development of agriculture in China had significant spatial disequilibrium characteristics, but the overall spatial differences continued to shrink, with regional differences being the main source of overall differences. Based on this, the core to solving the spatial imbalance problem of high-quality agricultural development in China was to narrow the gap in high-quality agricultural development between the four major regions.