The invention relates to an intelligent high-voltage cable heating and straightening all-in-one machine and a straightening method thereof. The intelligent high-voltage cable heating and straightening all-in-one machine comprises a bottom plate frame, an outer sleeve body, a right seal cover, a left end cover, a heating tube, a lower fixed V-shaped clamping block and a clamping device, wherein the outer sleeve body is arranged at the upper end of the bottom plate frame; the right end cover is arranged at the right end of the outer sleeve body; the left end cover is arranged at the left end of the outer sleeve body; the heating tube is arranged at the lower part of the left end or the lower part of the right end in the outer sleeve body; the lower fixed V-shaped clamping block is arranged at the upper end of the bottom plate frame along an X direction; and the clamping device is arranged in the outer sleeve body. The intelligent high-voltage cable heating and straightening all-in-one machine is compact in structure, reasonable in design, simple and convenient to operate and low in cost; the force application constancy is ensured; and the consistency of clamping force is always kept.