Warping machine is widely used equipment to warp beam for warp knitting machines. The yarn drop stop motion device is an important part of the warping machine. It can be used for a wide range of warping machines and sizing machines. The warper stop motion device for broken yarn adopts the principle of the lever through obturation. It can affect the stopping device of broken yarn. Being obturated, the sensitive action will not be affected by yarn scrap or dirt matter. Moreover, it is easy to maintain.