The invention discloses a one-time forming processing device of a square pipe hoop. The one-time forming processing device comprises a mold frame mechanism and a linkage extrusion mechanism, wherein the mold frame mechanism comprises a mold frame upper bottom plate, a guide sleeve, a guide column, a guide column fixing seat and a mold frame lower bottom plate; and the linkage extrusion mechanism comprises an upper punch, an upper fixing plate, a middle upper plate, an upper elastic body, a sliding block, a clamping block, a middle lower plate, a lower punch, a lower fixing plate and a lower elastic body. According to the one-time forming processing device of the square pipe hoop, one-time clamping and positioning are adopted in the production process, the positioning consistency is good, and the requirement for the shape and position tolerance of hoop bodies and a square through hole is fundamentally met; and the heights of the hoop bodies at the two ends and the symmetry of the hoop bodies are high, the hoop bodies are regular, the surface roughness is low, no crack distortion defect is caused, the consistency of the hoop bodies of the square pipe hoop is high, and the quality ofiron art subsequent assembly is ensured.