Based on panel data of 30 Chinese provinces from 1995 to 2020, a combination of mechanistic analysis and empirical testing was used to examine the spatial and temporal heterogeneity in the poverty reduction effect of labour mobility at the national, the time-stage and the regional levels respectively. The findings indicate that labor mobility brings positive effect to poverty alleviation in inflow areas through human capital agglomeration, resource allocation optimization and consumption upgrading, while it alleviates poverty in outflow areas through income transfer and return effects. At the national level, labour mobility has a poverty reduction effect. At the regional level, such an effect in central region is better than that in the eastern and western ones. At the temporal level, its effect has been reflected in the periods from 1995 to 2009(first stage) and from 2010 to 2020(second stage), and has been more pronounced after 2010. This paper provides both empirical evidence for an in-depth understanding on the spatial and temporal heterogeneity in the poverty reduction effect of labour mobility, and a basis for decision-making on the consalidating and expanding achievements of poverty dlimination and the in-depth promotion of rural revitalization.