The invention provides a square steel pipe column-concealed beam floor slab fabricated system adopting bolting-welding mixed connecting, and belongs to the technical field of structural engineering. The square steel pipe column-concealed beam floor slab fabricated system adopting bolting-welding mixed connecting comprises square steel pipe columns, concealed beam floor slab modules and bolting-welding mixed connecting joints. Beams prefabricated in a factory serve as frames of beam-slab overall modules, and prefabricated reinforced concrete is poured at the bottoms of the beams; in the construction site, the concealed beam floor slab modules and the square steel pipe columns are connected through the bolting-welding mixed connecting joints; then pipelines can be freely laid on prefabricated concrete layers, the pipelines between the different slabs penetrate through holes in beam webs, and after laying is completed, lightweight concrete is poured; and through beam-slab integration of the concealed beam floor slabs, both upper flanges and lower flanges of the beams are pre-embedded in the concrete of the floor slabs, thus the local stability of components is improved, and the problems of fire protection and corrosion prevention of steel structural beams are solved. Through the modes that the holes are formed in the webs and the floor slabs are poured in a layered mode, individualized arrangement and mounting of the pipelines are facilitated, and maintenance and transformation of the square steel pipe column-concealed beam floor slab fabricated system adopting bolting-weldingmixed connecting are convenient.