Abstract: The study of urban population spatialization in fine scale can help to analyze characteristics and influencing factors of population distribution, and provide data support for regional sustainable development．A population index system was established for Beijing with land cover data, river and road data, DEM data, night light data of Luojia-01 and point of interest data as influence factors．To solve the problem of complex and subjective method of determining weight of multi-source data in population spatialization, an objective and scientific principal component analysis method was proposed to mine data characteristics．Contribution rate of factors to the index evaluation system was used as weight to carry out multifactor weighted fusion, to realize fine spatialization of 30 m × 30 m population in Beijing．The accuracy of population spatialization (R²=0.85, E_MR = 0.28) was found to be better than Worldpop data (R²= 0.67, E_MR = 0.48)．The population in Beijing was found mainly distributed in the main urban area in the center, showing a decreasing trend of volatility outward, with multiple suburban sub centers in the periphery, a spatial distribution similar to density of interest points．All kinds of interest factors were given high weight, to be used as important indicator of spatial distribution of the Beijing population．This method might provide some reference for the study of spatial population in other cities．