Large-aperture string hole coaxiality and end face parallelism detection method

The invention relates to the technical field of coaxiality and parallelism detection, and particularly discloses a large-aperture string hole coaxiality and end face parallelism detection method, a detection tool needs to be adopted for coaxiality and parallelism detection, the detection tool comprises a supporting seat, two positioning columns and at least two supporting columns are arranged at the bottom of the supporting seat, the positioning columns are higher than the supporting columns, and the supporting columns are arranged on the supporting seat. A mounting rack is mounted on the supporting seat, and a dial indicator is mounted on the mounting rack; when the coaxiality and parallelism of a string hole and an end hole are detected, the two positioning columns of the supporting seat abut against the hole wall of the end hole, the supporting column is placed on the upper end face of the end hole, a probe of the dial indicator is attached to the hole wall or the end face of the string hole, then the posi