The utility model discloses a printing folding machine cutting machine. The printing folding machine cutting mechanism is characterized in that when a blade of a cutting knife does not turn to the cutter position, the cutting knife is located in a cutter groove and the blade is not higher than the opening; when the blade reaches above the cutter position, a control roll is contacted with a protruded portion of a wedge-shaped piece. With the cutting knife and the control roll rotating, a control portion inwards pushes the wedge-shaped piece, the wedge-shaped piece pushes the cutting knife downwards, and the blade cuts paper separate from top to down. After the cutting is finished, with the cutting knife and the control roll rotating, the control roll is separated from the protruded portion, and at the same time the blade is returned to the cutter groove through the act of an elastic part. The printing folding machine cutting mechanism has the advantage that the cutting knife can avoid in turning the blade.