From the perspective of household productivity, this paper analyzes the capital composition of the household and the formation mechanism of relative poverty. Based on the CFPS data in 2020, it uses the Alkire–Foster (AF) index to measure the breadth and depth of relative poverty in different regions and puts forward its governance mechanism. The results show that there are significant differences between urban and rural areas and among different regions. The relative poverty incidence rate is mainly concentrated in four indicators, accounting for 30.8% of the total number of indicators. From high to low, the incidences of relative poverty in a single dimension include financial assets, livelihood assets, health, and employment levels. The breadth is mainly reflected in economic capital, health, employment, and education level. The depth is reflected in financial assets, health level, and social network indicators. Except for the social capital dimension, the poverty in rural areas is higher than urban areas, and the central and western regions are higher than the eastern regions, showing a distinct characteristic of imbalanced urban–rural and regional development. This paper proposes the relative poverty governance mechanism of households’ capital accumulation, urban–rural integrated development and regional coordinated development.