The utility model discloses a dummy bar dismounting device is applied to the casting blank, the device includes: a pedestal. Draw quick -witted subassembly, be fixed in one end on the base, the control unit is used for receiving the position sigual of dummy bar, and according to position sigual sends to be used for rectifying and presses the strong pressure signal of casting blank, rectify quick -witted subassembly, be fixed in the other end on the base, wherein, draw the drive of quick -witted subassembly the slip of casting blank, it received to rectify quick -witted subassembly rectify and press behind the signal, it pushes down to rectify quick -witted subassembly the casting blank will the casting blank aligning, and under drawing the drive of machine, make the dummy bar with the casting blank breaks away from. The utility model provides an among the prior art dummy bar to dismantle the process complicated, and open and water the technical problem who has a big risk, has reached and has simplified the device, has improved to open and water the success rate and guarantee the stable technological effect of production.