Studying population flow patterns is essential for comprehending regional population changes and economic and social development trends. Using data from the sixth and seventh national population censuses to classify China's interprovincial population flows into four types: rural-urban, rural-rural, urban-urban, and urban-rural, this paper analyzes the spatial characteristics of population flow networks and their influencing factors using a spatial autoregressive negative binomial model. The results show that: The proportion of rural-urban and urban-urban population flows has increased, while the proportion of rural-rural population flows has decreased. Rural-rural and rural-urban population flows tend to move from west to east, while urban-urban and urban-rural population flows are diverse and bi-directional. China's population center is shifting from a single city (province) to an urban agglomeration. While economic factors play a significant role in rural-urban and rural-rural population flows, the factors influencing urban-rural and urban-urban population flows are complex and diverse. The degree of influence of economic factors on these flows is weakening.