The invention discloses a shift register, a drive method thereof, a gate drive circuit and a display device. The shift register comprises a signal input unit, a pull-up node boosting unit, a pull-up node buck unit, a pull-down node boosting unit, a pull-down node buck unit, a pull-up unit and a pull-down unit. The charging time of a gate scanning line can be changed only by changing high-level input signal output time of a signal end without changing factors such as a clock signal, a circuit structure and a related production process, so that the shift register can be applied to a product with a large size, an ultrahigh resolution, a high-frame scanning frequency and a narrow frame, the gate drive difficulty of the product with the large size, the ultrahigh resolution, the high-frame scanning frequency and the narrow frame is effectively reduced, production cost is reduced, and product competitiveness is improved.