The invention discloses a method for computing the density of population in road network grids on the basis of GIS (geographic information systems). The method includes mining and analyzing data of road networks; acquiring road network grid information corresponding to each person; computing the areas of the road network grids corresponding to each person so as to compute the numbers of the persons in the various road network grids; computing the density of the population in the various road network grids. The method has the advantages that the areas of corresponding map grids where each person is located are computed, accordingly, the density of the population in each road network grid can be computed, data support can be provided for designing bus lines, selecting sites for public toilets, arranging drugstores, selecting sites for public bicycle stations and the like, the method is scientific as compared with the traditional method, and living requirements of people can be effectively met.