Full-assembly type bridge erecting system and beam erecting and hole passing method

The invention discloses a full-assembly type bridge erecting system which comprises a main frame, a supporting leg system, a crown block system, an electrical system, a hydraulic system, a pier column mounting support and a cover beam mounting support. The supporting leg system comprises a front auxiliary supporting leg, a front supporting leg, a rear supporting leg and a rear auxiliary supporting leg, the front supporting leg and the rear supporting leg are each provided with a longitudinal moving assembly and a transverse moving assembly, and the front supporting leg and the rear supporting leg longitudinally move relative to the main beam through the longitudinal moving assemblies; the front supporting leg and the rear supporting leg drive the main frame to move transversely through the transverse moving assembly, the crown block system comprises a front crown block and a rear crown block, the pier column mounting support is arranged on a bridge bearing platform, and the cover beam mounting support is arra