The invention discloses a dummy centering device for a continuous casting sheet billet, belongs to the technical field of continuous casting equipment and aims to solve the problems of imprecise centering and long operation time of the dummy centering of the continuous casting sheet billet. The technical scheme is that the device consists of a base, a motor, a speed reducer, a screw rod, a screw nut, a tailstock spindle, a tailstock spindle sleeve and a tailstock ejector rod, wherein the motor is connected with the screw rod through the speed reducer; the screw nut is engaged with the screw rod; the tailstock spindle is arranged in the tailstock spindle sleeve; the screw nut is connected with the tailstock spindle; the tailstock ejector rod is arranged at the front end of the tailstock spindle; and four sets of the dummy centering devices are respectively arranged at the symmetrical positions on the sheet billet roller table at the raising part of a dummy rod. The device is characterized in that four sets of the dummy centering devices are respectively arranged at the symmetrical positions on the sheet billet roller table to realize the linkage of the four sets of the dummy centering devices, achieve the once precise positioning of the dummy rod opposite to different positions of the roller table and reduce the time of repeat regulation. The device has the advantages of simple structure, convenient use, precise regulation, quickness and convenient maintenance.