The invention discloses a laser ring imaging detector for the inside of a pipe body and a detection method of the laser ring imaging detector. The laser ring imaging detector comprises a mechanical part, a data transmission part, and a control and calculation imaging part, wherein the mechanical part comprises a machine body with a servo motor, umbrella-shaped internal supporting mechanisms, an umbrella-shaped feeding mechanism, an electric slip ring and a laser rotating mechanism; the umbrella-shaped internal supporting mechanisms are fixed on a machine body shell through bolts; the electric slip ring for preventing a signal transmission line from being twisted is arranged on the machine body at one end of an output shaft of the servo motor; the laser rotating mechanism is fixed at the top end of the output shaft of the servo motor; the umbrella-shaped feeding mechanism is arranged on the output shaft of the servo motor between the electric slip ring and the laser rotating mechanism; a laser sensor is arranged on the laser rotating mechanism. The detection method is simple, and can efficiently and accurately acquire corrosion information of the inner wall of a drilling rod and supply a technical support to improvement of the detection precision of the driving rod.