The utility model discloses a lower die bottom of a steel pipe pressure straightening machine. The lower die bottom comprises a lower die body and a moving device which is arranged at the lower end of the lower die body and enables the lower die body to move horizontally under the effect of external force. Through the moving device, the distance of two lower dies can be conveniently adjusted, namely the distance of supporting points of a straightened steel pipe is adjusted, a better steel pipe three-point anti-bend straightening effect is obtained, labor intensity of workers is lowered, and production efficiency is improved.