The utility model relates to a bidirectional size adjusting device of a steel reinforcement framework forming machine. The bidirectional size adjusting device comprises a reverse screw mechanism and two groups of slide block mechanisms, wherein the reverse screw mechanism consists of an adjusting lead screw and lead screw nuts, and the thread directions of the two ends of the adjusting lead screw are reversed; the slide block mechanisms consist of links I, links II, sliding blocks I, sliding blocks II, a fixed longitudinal beam and a movable longitudinal beam, and the two groups of slide block mechanisms are symmetrically arranged at the two ends of the adjusting lead screw; the adjustment on the cross section size of a steel reinforcement framework is realized through fixing the sliding blocks I and the sliding blocks II, controlling the adjusting lead screw to turn and the lead screw nuts to move, enabling included angles between the links I and the links II to be increased or decreased, driving the movable longitudinal beam to move by the sliding blocks II and increasing or decreasing the vertical spacing between the movable longitudinal beam and the fixed longitudinal beam; the adjustment on the longitudinal size of the steel reinforcement framework is realized through fixing the movable longitudinal beam, controlling the adjusting lead screw to turn and the lead screw nuts to move and enabling the links I and the links II to respectively drive the sliding blocks I and the sliding blocks II to horizontally move on the fixed longitudinal beam and the movable longitudinal beam.