Abstract: Based on panel data from 1874 counties in China from 2013 to 2021, this study employs bidirectional fixed effect models and nonlinear mediation models to examine the impact of county-level industrial integration on the urban-rural income gap and its underlying mechanisms.The results reveal a significant U-shaped nonlinear relationship between industrial integration and income gap:At lower levels of industrial integration, it helps reduce the urban-rural income gap, while at higher levels, it exacerbates the gap.However, most counties in China have not yet reached the inflection point where the income gap begins to widen.Mechanism analysis shows that county-level industrial integration affects income gap through two main channels:promoting industrial upgrading and advancing urbanization.Long-term effect analysis indicates a second inflection point where high levels of industrial integration further reduce the income gap.These findings suggest that the government should strengthen infrastructure and institutional development based on the characteristics of county-level industrial development, and promote the integration of county-level industries in a systematic manner to effectively narrow the urban-rural income gap.

Key words: industrial integration development, urban-rural income gap, industrial structure upgrading, urbanization