Based on the previous studies, linking labor force transfer, agricultural technology level and urban-rural income gap, we can specifically examine the impact of labor transfer on urban-rural income gap. Using the provincial panel data of China from 2009 to 2019, this paper takes agricultural technology level as the threshold variable, the Theil index as urban-rural income gap, labor transfer as the core explanatory variables to construct a panel threshold mode which empirically concludes that labor transfer has an nonlinear impact of on the urban-rural income gap. It is found that the transfer of labor force can reduce the income gap between urban and rural areas, and the effect has a single threshold effect. When the agricultural technology is in low level, the effect of labor transfer on the convergence of the urban-rural income gap is small; when the agricultural technology level crosses the threshold and enters the higher level, the effect of labor transfer on narrowing the urban-rural income gap almost increases doubled. By replacing the explanatory variable Theil index with the ratio of per capita disposable income in urban and rural areas, and the core explanatory variable agricultural technology level with agricultural production efficiency, the robustness test shows the above conclusion still holds.In this paper, the three important variables of agricultural technology progress, labor force transfer and the urban-rural income gap are brought into one model framework. While deepening the research from the perspective of labor mobility affecting the urban-rural income gap, it provides an important reference for the formulation of the policy of narrowing the urban-rural income gap.