In order to solve the wear repair problem of large steam turbine rotor shaft journal, the material of steam turbine rotor shaft as substrate and the self-made special laser cladding remanufacturing powder as experimental material, the experiments were carried out by laser cladding remanufacturing method based on laser cladding remanufacturing system with coaxial powder feeder. Focusing on effect of different width of laser cladding layers on total indicated runout (TIR) of steam turbine rotor, the experiment research and mechanism simulation verification were performed, and the influence mechanism of different factors were analyzed. The results show that the data results of total indicated runout are closely related to probe diameter and laser cladding layer width. The width of cladding layer determines the turbine rotor surface magnetic, eddy current density and magnetic flux density distribution. Due to the interference of matrix magnetic field and eddy current density of surface, the magnetic flux density suddenly changes in the laser cladding layer edge when the laser cladding layer width is less than 8mm.The measurement results are too large caused by the comprehensive effect of substrate and laser cladding layer. According to the numerical simulation of magnetic flux density distribution of measured metal body surface, the critical value of laser cladding width is 9.82mm.