The invention discloses an anti-falling device with a manual reset capacity for a boiler slag stopper. The scheme is as follows: firstly, a position where the slag stopper cannot turn and fall out of a slag discharge machine and can stand vertically is found out on the spot, and a through hole with an inner diameter of 60 mm is drilled by a super hole cutter in a rear boiler wall corresponding to each slag stopper; then a steel pipe with the aperture of 50 mm is taken as a casing pipe whose length is equal to the thickness of the boiler wall, and is inserted from an external boiler wall, and a cavity of the pipe in the boiler wall is mended by refractory cement; a pipe with the aperture of 40 mm is taken as an anti-falling pipe whose length is equal to a distance between a point which can support at the back when the slag stopper is erected and the rear boiler wall plus the thickness of the rear boiler wall and plus 300 mm; and a steel pipe with the thickness of 25 mm and the length of 200 mm is used as a horizontal pipe, and the horizontal pipe is welded on the anti-falling pipe according to the interval equal to the distance between the anti-falling pipe and the wall bottom, and is used as an anti-falling pipe reset device each of which is mounted corresponding to each slag stopper. The anti-falling device has the benefits of simple structure, convenience in installation, durability and reliable use.