This study selects Beijing-Tianjin-Hebei region as the study area and attempts to realize the population spatialization with the data of DMSP/OLS, land use, socio-economic and ecological environmental factors related to population distribution at the medium scale. Firstly, the authors obtain the census data of Beijing-Tianjin-Hebei region in 2010, and then calculated the probability coefficient based on these factors (selected roads, railways, rivers, slope, land use and nighttime light), and finally assign the census data to each pixel using all related variables and their probability coefficients with the software of geographic information system (GIS). City census data was chosen to test the research result, and the results showed that the accuracy rate of the population spatialization in the Beijing-Tianjin-Hebei region is more than 74% in the urban scale. The method for population spatialization can be well applied to the spatialization of demographic data at medium scale.