The invention provides a fabricated concrete building close-column system. Light mortar is sprayed into spaces between square prefabricated concrete wall columns, so that a bearing wall is formed. An insulation and decoration integrated board is mounted on the outer side of the bearing wall, and a gypsum board is mounted on the inner side of the bearing wall. The square prefabricated concrete wall columns and special-shaped prefabricated concrete corner columns are divided into a plurality of layers, and all the layers are connected through prefabricated concrete beams. Sleeves are embedded in the upper ends of the square prefabricated concrete wall columns and the upper ends of the special-shaped prefabricated concrete corner columns, and the lower ends of the square prefabricated concrete wall columns and the lower ends of the special-shaped prefabricated concrete corner columns are fixed into a prefabricated strip-shaped foundation provided with openings or into openings of the prefabricated concrete beams. Bolt holes are formed in the openings of the prefabricated concrete beams, and bolts penetrate through the bolt holes to be connected with the square prefabricated concrete wall columns below the prefabricated concrete beams and/or the sleeves embedded in the upper ends of the special-shaped prefabricated concrete corner columns. Prestressed laminated boards are adopted for the floor and the roof, and a prefabricated dormer is adopted to serve as a pitched roof dormer. The fabricated concrete building close-column system is formed by splicing and assembling prefabricated concrete components on site, and the components are connected through the bolts, so that the field construction workload is reduced, and the assembling rate and the construction speed are increased.