Insulation duct structure is provided to allow duct assembly and installation work to be simplified by completing duct the assembly and installation work after inserting panels into panel connection bars, and inserting the panel connection bars into coupling nuts, and to provide excellent insulation effect by panels having a plurality of independent partition rooms. Insulation duct structure comprises four panels(20,30,40,50), panel connection bars(60,70,80,90), coupling nuts(100,110,120), and bolts. The four panels forms four surfaces of a duct, and has a plurality of independent partition rooms. The panel connection bars forms four corner parts of the duct, and connects the four panels. The coupling nuts are connected to the panel connection bars so as to be transported along the length direction. The bolts are connected to a ceiling of the coupling nuts and support the duct.
