The invention discloses an active stress eliminating device for loose sand and gravel geology tunnel construction, and relates to the technical field of tunnel construction. The active stress eliminating device for loose sand and gravel geology tunnel construction comprises a baffle arch, the upper surfaces of two locating feet are welded to the two ends of the baffle arch respectively, the bafflearch is provided with seams circumferentially arranged by taking the center of the circle of the baffle arch as the center, anchor holes are formed in the baffle arch which is internally provided with a cavity, 13 export holes communicated with the cavity are formed in the middle of the outer side face of the baffle arch, and inclined holes communicated with the cavity are formed in the portions,corresponding to the export holes, of the back and the front of the baffle arch. According to the active stress eliminating device for loose sand and gravel geology tunnel construction, by means of aspecial-shaped transmission bag in a pneumatic extrusion mechanism, an extrusion stem and an injection mechanism can be pushed, the inner wall of a tunnel is rapidly and effectively supported, and the influence of stress on tunnel inner wall structure is rapidly reduced.