Based on the panel data of 276 prefecture-level cities in China from 2009 to 2018, this paper explores the impact of the agricultural productive service industry on the income gap between urban and rural residents by constructing the spatial econometric model and threshold regression model. The results show that the development of the agricultural productive service industry has a significant spatial spillover effect, which has a significant restraining effect on widening the income gap between urban and rural residents in the neighboring areas. Developing the agricultural productive service industry in the eastern and central regions significantly narrows the income gap between urban and rural residents. There is a significant urbanization threshold effect on the impact of the agricultural productive service industry on the income gap between urban and rural residents. When the urbanization level crosses the threshold of 3.7469, the role of the agricultural productive service industry in reducing the income gap between urban and rural residents increases significantly. Therefore, this paper proposes accelerating the development of the agricultural productive service industry, improving the urban–rural integration mechanism, strengthening the coordinated development between regions and playing the external effects of the agricultural productive service industry.