The invention discloses a method for climbing a vertical ladder. The method comprises the following steps that a, a lifting rope is buckled with a vertical ladder climbing person, wherein the lifting rope is wound around a winding drum, the winding drum is rotationally mounted on a transverse supporting rod at the top of the vertical ladder and is in driving connection with a driving motor, and a rotary shaft of the winding drum is rotationally connected with a brake signal transmitting structure and a brake structure; and b, when the vertical ladder climbing person climbs upwards, the driving motor lifts the lifting rope and assists the vertical ladder climbing person in climbing upwards, the driving motor is stopped when the vertical ladder climbing person climbs down, the brake signal transmitting structure acquires the rotating speed of the winding drum in real time, whether the vertical ladder climbing person falls off or not is judged through the rotating speed, and the brake signal transmitting structure triggers the brake structure to stop the winding drum from rotating to prevent falling when the vertical ladder climbing person falls off. According to the method for climbing the vertical ladder, more labor can be saved when the person climbs the vertical ladder, falling prevention can be achieved better, and the safety of the safety climbing person is ensured.