The invention discloses a sorting and stacking system for an injection molding machine. The sorting and stacking system comprises a conveying unit, a code jet-printing unit, a robot, a stacking unit,a three-coordinate manipulator and an injection molding machine. The three-coordinate manipulator grabs workpieces from the injection molding machine and puts the workpieces on the conveying unit. Theconveying unit conveys the workpieces to a taking opening of the robot. The robot sequentially completes workpiece grabbing, two-dimensional code jet-printing and stacking according commands, finallythe workpieces are conveyed to a manual discharging opening through a support roller conveying line, and discharging is completed. The sorting and stacking system can achieve sorting, stacking and two-dimensional code jet-printing of various materials different in profiles, and the adaptability and the cost performance of the system are high.