The utility model discloses a square steel confined concrete arch center back filling bolt-grouting retaining and protecting system. The square steel confined concrete arch center back filling bolt-grouting retaining and protecting system comprises a high-strength anchor bolt, a grouting anchor bolt, a grouting anchor cable and a plurality of square steel confined concrete arch centers, wherein every two adjacent square steel confined concrete arch centers are connected through a longitudinal beam provided with an anchor bolt hole, a longitudinal beam anchor bolt penetrates through each longitudinal beam through the corresponding anchor bolt hole and is anchored into surrounding rock, a back filling layer is arranged between each square steel confined concrete arch center and the surrounding rock, and the square steel confined concrete arch centers, the back filling layers and the tunnel surrounding rock are connected together through the longitudinal beam anchor bolts; the high-strength anchor bolt, the grouting anchor bolt and the grouting anchor cable are struck before the square steel confined concrete arch centers are erected. The square steel confined concrete arch center back filling bolt-grouting retaining and protecting system is suitable for retaining and supporting of soft and broken surrounding rock tunnels and other underground engineering, has the advantages of being high in strength, good in stability, reasonable in stress and the like, and can effectively improve primary retaining and protecting strength after the tunnels are excavated and guarantee stability of the tunnel surrounding rock.