The invention provides an anti-falling device and an anti-falling method. The anti-falling device comprises a guide rail, a self-locking device, a safety belt and the like, wherein the guide rail is provided with at least one clamping seat which protrudes the matrix surface of the guide rail, the upper end face of the clamping seat is a clamping face clamped and braked with a clamping block of the self-locking device, and the height of the clamping seat is gradually reduced from the clamping face of the upper end to the part of the lower end protruding the matrix of the guide rail; and the self-locking device comprises the clamping block and a body, wherein the clamping block is movably connected with the body through a rotating pin shaft, the clamping block is provided with a clamping head, the clamping block can rotate by using the rotating pin shaft as a center, and the clamping head extends out of the bottom surface of the body to realize locking braking with the clamping seat on the guide rail. The anti-falling device has better stress performance, and has safer and more reliable braking performance between the guide rail and the self-locking device; and by using the device and the method, normal action and overhauling operation of an operator are not affected at the same time of protecting the safety of the operator.