The invention relates to the technical field of railway construction and discloses a jack stabilizing device. The jack stabilizing device comprises a base (10) in a plane shape and a containing body (11) installed on the base (10) and used for containing a jack; the end, away from the base (10), of the containing body (11) forms an opening (110); and the side wall of the containing body (11) is provided with a first opening (111) extending in the height direction of the containing body (11) and used for operating a rasp bar of the jack. The jack stabilizing device can contain the jack so that it can be prevented that the jack in operation waggles and the stability of the jack can be improved, and the safety of operating personnel is guaranteed; and meanwhile, the jack is not prone to side sliding, and the jack cannot fly out or be damaged.