Using the 2013 and 2018 household survey data of the China Household Income Project (CHIP), we analyze the changing characteristics of the urban-rural income gap and the cause of it from the human capital perspective. It is found that the urban per capita income is higher than that of the rural areas and its internal gap is smaller. The urban-rural income gap decreases with the increase of the income quantile, and the urban-rural income ratio of the low-income group increases greatly in two years. The overall inequality index changed little over the two years, with the gap between groups declining, but the gap within groups increasing. Due to the large proportion of urban population and income, the contribution of urban areas to the national inequality index is greater than that of rural areas, and has increased in the two years. Based on the income function and its decomposition, the urban and education variables are the main contributing factors of the overall income inequality, and the coefficient of urban variable decreases with the increase of the income quantile. Education is the main contributor to the endowment effect of the income gap between urban and rural groups, and the education endowment effect increases with the increase of the income quantile. In 2018, the education endowment effect of middleincome groups is the largest. The coefficient effect decreases with the increase of the income quantile.