The utility model discloses a connection limiting device for welding connecting plates in tunnel steel arches. The connection limiting device comprises a positioning plate. Positioning posts for positioning fit with connection holes of a connecting plate are arranged on the surface of the positioning plate. Limit fasteners which are rotatable are hinged to two sides of the positioning plate respectively. The inner side of each limit fastener is provided with a fastening channel used for fastening and positioning a steel arch. A lock unit for connecting and locking the limit fasteners is disposed between the limit fasteners arranged on two sides of the positioning plate. The lock unit comprises a lock rod and a lock post; the lock rod is hinged to one limit fastener; the lock post is arranged on the other limit fastener; the end of the lock rod is provided with a lock hook used for being locked to the lock post so as to connect and lock the limit fasteners. The connection limiting device has the advantages that fixation of the steel arch and the connecting plate can be achieved, axis deviation can meet the requirement after the steel arch is connected, the connection holes of the connecting plates can be accurately aligned when two steel arches are connected, quality of the arch structure is ensured, and the connection limiting device allows firm and stable fixation and is convenient and quick to operate and simple in structure.