The utility model discloses a modular expansion and contraction device with an adjustable steel plate anchoring member. The device comprises a side beam, a middle beam, a supporting cross beam, an elastic displacement device and a side beam anchoring system, wherein the side beam anchoring system is that effective connection and anchoring of the side beam and the main beam are realized through a connecting steel plate welded to the side beam, transverse round steel, an adjustable anchoring steel plate and a U-shaped anchoring reinforcement welded on a supporting cross beam box and a side plate of a displacement box body; the middle beam is supported against the transverse supporting beam and is connected with the supporting cross beam through a fixing bolt; a bridge expansion and contraction device is realized after the displacement box body is fixed to the side beam or the middle beam. The problems such as poor anchoring performance, difficulty in construction and mounting, high probability of breakage of the main beam, failed displacement system and the like of the existing bridge modular expansion and contraction device, so the service life of the bridge modular expansion and contraction device is prolonged.