<p>Terrain slope is a pivotal environmental factor influencing population distribution. With China's rapid urbanization, urban and rural populations have been redistributed. However, the distribution and change of urban and rural populations across slope gradients in China remain underexplored. Using a digital elevation model and multi-temporal spatial population datasets, we conducted a comparative analysis of urban and rural areas to investigate population distribution and its changes across slope gradients in China from 2000 to 2020 at both national and provincial scales. Our results show that: (1) from 2000 to 2020, the pattern of 'urban increase and rural decrease' in population proportion generally occurred across all slope sections, and in every period for each statistical unit, the proportion of urban population always decreased with increasing slope; and (2) in most provinces, the urban and rural populations both maintained an L-shaped distribution across slope gradients. The mean slope of population distribution in both urban and rural areas tended to increase, although the mean slope for the urban population was generally lower than that for the rural population. These results provide new insights into population distribution and change characteristics in urban and rural areas. Our findings suggest that the influence of the slope factor should be fully considered when designing policies to optimize the spatial distribution of population.</p>