The invention relates to a curved channel waveguide slow-wave line, belonging to the technical field of microwave electronic tubes and relating to a slow-wave line structure in a microwave tube high-frequency system. The slow-wave line is formed by bending the channel back and forth by the channel waveguide along a direction of the channel; an electric field of a ground mode in the channel waveguide is the strongest on the vertical axis of the slow-wave line and generates the strongest interaction right with an electron bunch; a gap is left between an upper metal plate and a lower metal plateof the channel waveguide without special electron bunch channels; and a side wall for supporting the gap between the upper and lower metal plates can be made of metal, insulating materials or microwave absorption materials. The curved channel waveguide keeps the advantages of large size, low consumption and wide band of the channel waveguide, and the curved channel waveguide slow-wave line also allows large-size electron bunch to pass through, thereby having higher output power and efficiency. At the same time, the slow-wave line has the characteristics of relatively simple structure, low processing precision requirement and easy processing. The curved channel waveguide slow-wave line is more suitable to be applied in the travelling wave tube of the wave segments of millimeter wave and submillimeter wave.