Square support suitable for downward filling mining method

The square support suitable for the downward filling mining method comprises a support cross beam and support legs arranged at the two ends of the support cross beam respectively, each support leg comprises an upper support leg and a lower support leg, the upper end of each upper support leg is fixedly connected with a connecting sleeve, the connecting sleeves are arranged on the support cross beam in a sleeved mode, and the lower ends of the connecting sleeves are connected with the lower ends of the lower support legs. The lower ends of the support upper legs are fixedly bound with the upper ends of the support lower legs. The lower ends of the support lower legs are fixed to a roadway bottom plate. A support side support is further arranged between the support beam and the support upper leg, one end of the support side support is movably connected with the support upper leg, and the other end of the support side support abuts against and is fixed to the support beam through connecting angle steel fixed to