The present invention relates to a bidirectional fixation steel plate and a bone shaft fixation system. The bidirectional fixation steel plate comprises a steel plate body, wherein the steel plate body is used to be implanted from a front side of a bone shaft and has a structure matched with the front side of the bone shaft to fixedly fit with a fracture end, the steel plate body is provided with at least two pairs of guide holes for first locking screws to pass through respectively in the structure matched with the front side of the bone shaft, and angles of the guide holes enable the first locking screws passing through to clamp an intramedullary nail together to control rotation and axial stability of the intramedullary nail. The bidirectional fixation steel plate proposed by the present invention may achieve support, anti-rotation and axial stability of the bone shaft fracture end through the cooperation of the first locking screws and the guide holes of the steel plate body provided with specific angles, to further enhance the reliability of fixation after reduction, thereby effectively guaranteeing to assist in stable reduction and healing of the fracture site.