The utility model discloses an inside support device for steel pipe straightening and relates to the technical field of steel pipe straightening. The inside support device for the steel pipe straightening comprises an upper inside support die, a lower inside support die, a jack and a traveling device, the upper inside support die is an upper support frame with an upper circular arc-shaped support surface, the lower inside support die is a lower support frame with a lower circular arc-shaped support surface, the upper support frame is abutted to the lower support frame in the vertical direction, the upper circular arc-shaped support surface and the lower circular arc-shaped support surface are symmetrically arranged in the vertical direction, the upper support frame is provided with an upper horizontal plate, the lower support frame is provided with a lower horizontal plate, the pedestal of the jack is fixed with the lower horizontal plate, the top post of the jack is fixed with the upper horizontal plate, the traveling device is a rectangular framework with universal wheels, and the lower support frame is located in the rectangular framework. The inside support device for the steel pipe straightening is capable of playing a role of supporting in a steel pipe when straightening the steel pipe so as to prevent the steel pipe from deformation due to excessive pressure.