The invention is applicable to the technical field of power tubular bus bars, and provides a power tubular bus bar expansion and shrinkage monitoring device and a power tubular bus bar expansion and shrinkage monitoring method. The power tubular bus bar expansion and shrinkage monitoring device comprises a motion conversion mechanism and a holder for fixing the whole device, the motion conversion mechanism comprises a driving rod and a rotary shaft, a pointer is fixed on one end of the rotary shaft, which passes through a dial, and when the driving rod is pushed to move, the pointer can rotate along with the rotary shaft. The invention utilizes the motion conversion mechanism to amplify and convert the linear displacement of a power tubular bus into the angular displacement of the rotary shaft, moreover, the angular displacement is indicated by the pointer on the dial, and thereby managing personnel can conveniently, visually and accurately observe.