The invention discloses an automatic operation system of a drilling string. The automatic operation system mainly consists of an automatic catwalk machine, a drilling floor manipulator, a power clip, an iron driller, a power hanging clip, a monkey board pipe arrangement manipulator, a top drive, a winch, a driller integrating control system and the like. The automatic operation system has the advantages that after the automatic operation system is arranged on a petroleum drilling machine, the automatic drilling operations, such as lifting and lowering of the drilling string in the drilling floor, drilling, drill lifting, drill lowering, and stand discharging, are realized; the automation degree of the drilling machine is improved, and the problems of high labor intensity, high risk and low efficiency caused by overhead operation and multi-person matching operation in the existing drilling string operation method are solved; the defects of decreasing of local labor intensity, and failure of reducing of number of operators and improvement of operation efficiency caused by using of one or several automatic devices of the existing drilling machine are overcome.