Abstract: Promoting common prosperity and increasing residents' income is a crucial task in China. As one of the most rapidly developed transportation infrastructure, high-speed railway (HSR) plays a pivotal role in enhancing residents' income. This study evaluated the accessibility of HSR networks in Jiangsu, Zhejiang, and Shanghai from new perspectives of internal and external accessibility for the years of 2012, 2016, and 2020. Furthermore, this study analyzed the coupling and coordination development between HSR accessibility and residents' income. The findings were: (1) The overall HSR accessibility was gradually increasing; However, there existed an imbalance in the spatial distribution with higher accessibility in Shanghai, Central Jiangsu, Southern Jiangsu, and Northern Zhejiang, compared to Northern Jiangsu and Southern Zhejiang. (2) Among the studied regions, Shanghai demonstrated the highest income level, followed by Southern Jiangsu and Southeastern Zhejiang. Central Jiangsu along with Southwestern Zhejiang were ranked the next, while Northern Jiangsu was lagged behind. (3) Most cities exhibited a coherent developmental relationship between HSR accessibility and residents' income; However, when comparing internal versus external accessibility measures, the coupling coordination degree between internal accessibility and residents' income demonstrated a slower growth. (4) In Northern Jiangsu, the HSR development outpaced the improvement rate of residents’ income level, which indicated a need of an enhanced utilization of HSR infrastructure. Conversely, in Southeastern Zhejiang, the slower pace of internal transportation infrastructure development hampered resident's income growth, resulting in an imbalanced relationship. It was imperative to strengthen transportation links between HSR stations and surrounding areas within this region. In summary, the enhancement of HSR network accessibility promoted residents' income. However, the sluggish development of the internal HSR transportation network in certain regions hampered residents' income growth. In order to foster residents' income and expedite coordinated regional development, it is imperative to strategically advance HSR alongside other transportation infrastructure.