The Belt and Road (B&R) policy is a region-oriented economic policy implemented by the Chinese government since 2010, involving the largest population and covering the largest area in the world. Whether it can significantly narrow the income gap between Han and ethnic minority residents has not been investigated in the literature. To avoid endogenous problems in the model, we used the spatial breakpoint regression method to investigate 2,037 county-level administrative regions in China from 2014 to 2021 and empirically evaluated the impact of the policy on the income gap between Han and ethnic minority residents. Results show that, compared to the counties without B&R policy, the average income gap between minority counties with B&R and Han has increased by 1.468–1.518 times, which was nearly 1.3 times the sample mean of survey data, indicating that the income gap has been widened significantly by B&R. However, the policy has a narrowing effect on the income gap between minorities and Han in the 20% sample with the widest income gap between minorities and Han. From the dynamic effect of years, with the effect of B&R, the income gap between minorities and Han is an inverted U-shaped curve, first increasing and then decreasing.