The invention relates to a bus duct. A casing composed of side plates and a cover plate is internally provided with a phase wire conductor, the side plates and the cover plate are connected side coverplates formed through one-time pultrusion molding, segments of the bus duct are connected through splicers, joint bolt end portions of the splicers, joint nuts and joint pressure plates among outer-most-layer insulation baffle plates are formed by section bars through one-time pultrusion molding, cross sections of the section bars are generally C-shaped structures, two-side wing edges of the C-shaped structures are provided with multiple heat radiation reinforcement ribs facing towards an inner side of the phase wire conductor of the bus duct, a groove is mounted between the adjacent heat radiation reinforcement ribs, an inner side is provided with a limit groove for limiting side plate connection members, and disc-shaped springs are clamped in inner chambers of the C-shaped structures ofsplicer pressure plates. The bus duct is advantaged in that mutual matching mounting of grooves of heat radiation ribs of cross section U-shaped structures of the side plate connection members and mounting grooves of the joint pressure plates is carried out, the internal air contact area of the side plate connection members, joint plates and joint portions of the bus duct is enhanced through theheat radiation reinforcement ribs, heat radiation efficiency is high, the quantity of parts is small, connection is reliable, mounting and transportation are convenient, and corrosion resistance performance is good.