Abstract: To explore the internal mechanism of environmental pollution on urban-rural income gap, the inter-provincial panel data of China from 2000 to 2018 were used as samples to construct intertemporal economic model and threshold effect through theoretical and empirical analysis. The results show that environmental pollution significantly widens the gap between urban and rural incomes. This conclusion is consistent with the results of the metrological test with COD and SO₂ as the main explanatory variables. The negative externality of the negative cumulative effect exists in the urban-rural income gap. When the urban-rural income gap is larger at the beginning of the period, the positive effect of environmental pollution on the urban-rural income gap is stronger with the increase of the threshold range. Nevertheless the impact of public service expenditure, urbanization level and industrial structure upgrading on the urban-rural income gap cannot be ignored.