The utility model discloses a bag manufacturing machine, first send roll frame and second send roll frame all the hinge connect on the lathe, be convenient for adjust the bracket height, the second send a roll frame front end to be equipped with overspeed device tensioner, overspeed device tensioner includes tensioning cylinder, link and tensioning roller, the tensioning cylinder is fixed in on the lathe, the tensioning roller is located the link, the link passes through the piston rod and links to each other with the tensioning cylinder, can improve the tension of plastic film, be equipped with reset spring between piston rod and clamp plate, the recovering of the clamp plate of being convenient for, the lathe end is equipped with the collection frame, the collection of the sack of being convenient for, and this bag manufacturing machine has work efficiency height, advantage that degree of automation is high, has wide market prospect.