The invention aims to provide a method for mounting an escaped smoke collection device on line in a pushing way, which has the advantages of saving of mounting time, rapid construction and safe operation under the condition that a coke oven does not stop. The method comprises the following steps: fixing support columns to resistance walls; movably assembling a mounting trolley on a coal charging car rail: firstly, assembling a first-segment dust cage on the mounting trolley, pushing a first support transverse beam to the side part of a coal tower, and mounting the first-segment dust cage after placing the first support transverse beam on two support columns through a jack; fixedly connecting the first support transverse beam and the support columns; fixedly connecting the front end of the first-segment dust cage and the coal tower; assembling a middle-segment dust cage on the mounting trolley, pushing the mounting trolley to a mounting position, and hanging the middle-segment dust cage on the coal tower through a cable; lastly, assembling a tail-segment dust cage on the mounting trolley, pushing the tail-segment dust cage to the mounting position together with a second support transverse beam, placing the second support transverse beam on the two support columns through the jack, and mounting the tail-segment dust cage.