A shift register for scanning a display device including at least three shift register unit circuits, wherein each of the at least three shift register unit circuits comprises: a first Thin Film Transistor TFT (M101; M201; M301) having a gate connected to a frame start signal input terminal, a first electrode configured to be connected to a switching-off voltage signal input terminal, an operating voltage input terminal or a grounding voltage input terminal according to a position where the shift register unit circuit is located in the shift register, and a second electrode connected to a pull-up node; a second TFT (M102;M202; M302) having a gate connected to a second electrode of the first TFT, a second electrode connected to a forward clock signal input terminal, and a first electrode connected to a signal output terminal (OUTPUT); a third TFT (M103; M203; M303) having a gate connected to a signal input terminal (INPUT), a second electrode connected to the operating voltage input terminal, and a first electrode connected to the second electrode of the first TFT; a fourth TFT (M104; M204; M304) having a gate connected to a signal reset terminal (RESET), a second electrode connected to the first electrode of the third TFT, and a first electrode connected to the grounding voltage input terminal; a fifth TFT (M105; M205; M305) having a gate connected to a reverse clock signal input terminal (CLKB), a second electrode connected to the signal output terminal (OUTPUT), and a first electrode connected to the switching-off voltage signal input terminal; and a capacitor (C101; C201; C301) having a first electrode connected to the second electrode of the first TFT and a second electrode connected to the signal output terminal (OUTPUT); wherein when the shift register unit circuit is located at a first position of the shift register, corresponding to a first row of the display device, the first electrode of the first TFT is connected to the operating voltage input terminal; when the shift register unit circuit is located at a middle position of the shift register, corresponding to a middle row of said display device, the first electrode of the first TFT is connected to the switching-off voltage signal input terminal; and when the shift register unit circuit is located at a last position of the shift register, corresponding to a last row of said display device, the first electrode of the first TFT is connected to the grounding voltage input terminal. a first Thin Film Transistor TFT (M101; M201; M301) having a gate connected to a frame start signal input terminal, a first electrode configured to be connected to a switching-off voltage signal input terminal, an operating voltage input terminal or a grounding voltage input terminal according to a position where the shift register unit circuit is located in the shift register, and a second electrode connected to a pull-up node; a second TFT (M102;M202; M302) having a gate connected to a second electrode of the first TFT, a second electrode connected to a forward clock signal input terminal, and a first electrode connected to a signal output terminal (OUTPUT); a third TFT (M103; M203; M303) having a gate connected to a signal input terminal (INPUT), a second electrode connected to the operating voltage input terminal, and a first electrode connected to the second electrode of the first TFT; a fourth TFT (M104; M204; M304) having a gate connected to a signal reset terminal (RESET), a second electrode connected to the first electrode of the third TFT, and a first electrode connected to the grounding voltage input terminal; a fifth TFT (M105; M205; M305) having a gate connected to a reverse clock signal input terminal (CLKB), a second electrode connected to the signal output terminal (OUTPUT), and a first electrode connected to the switching-off voltage signal input terminal; and a capacitor (C101; C201; C301) having a first electrode connected to the second electrode of the first TFT and a second electrode connected to the signal output terminal (OUTPUT); wherein when the shift register unit circuit is located at a first position of the shift register, corresponding to a first row of the display device, the first electrode of the first TFT is connected to the operating voltage input terminal; when the shift register unit circuit is located at a middle position of the shift register, corresponding to a middle row of said display device, the first electrode of the first TFT is connected to the switching-off voltage signal input terminal; and when the shift register unit circuit is located at a last position of the shift register, corresponding to a last row of said display device, the first electrode of the first TFT is connected to the grounding voltage input terminal.