A construction method of large-section through circular tube steel members includes the steps of (1), performing three-dimensional full-simulation modeling on a circular tube steel member through Creo soft; (2), subjecting the three-dimensional full-simulation modeling to lofting and expansion; (3), importing 1:1 planar graph to Sinocam software to program a cutting process to acquire a steel plate cutting process file; (4), blanking accurately by a full-automatic cutting machine tool according to the cutting process file; (5), shaping by rolling the steel plates on a rolling machine; (6), subjecting the circular tube steel member shaped by rolling to the process of closing and longitudinal seam welding; (7), subjecting the welded circular tube steel member on the rolling machine to the process of rounding; (8), cutting off the length margin of the circular tube steel member. The cutting end is positioned at the opposite side of the one end of the through opening of the circular tube steel member. The construction method solves the technical problems that high consumption of materials is needed, it is difficult to guarantee cutting quality and precision, and production efficiency is low in use of the conventional processing method.