Abstract: Embodiments of the present disclosure disclose an expansion connector for connecting square tubes comprising a base and a square column movably connected to the base. The square column is movable relatively to an end of the base. A first expansion piece and a second expansion piece are sleeved on the square column. The first expansion piece has a first insertion groove on a side. The first expansion piece has a first insertion piece on one end. The first insertion piece has a first bending portion which is in contact with the square column. The second expansion piece has a second insertion groove on a side. The second expansion piece has a second insertion piece on one end. The second insertion piece has a second bending portion which is in contact with the square column.