Abstract: Air-gap eccentricity commonly occurs in large induction motors, especially submersible motors. Based on this failure, a curved eccentricity model is set up by simulating the deflection of the shaft and such model is applied to prototype (1 200kW submersible motor) and current analysis of the faulty machine is carried out in this paper. Then, the amplitude of the unbalanced magnetic force is calculated by analyzing the influence of the air gap on the magnetic field and 3-D finite element method is carried out to calculate UMP in curved eccentric motor. By comparing the amplitude of the vibration signal spectrum and current signal spectrum, the existence of curved eccentricity can be detected. The result proves the feasibility of such dual signal analysis on curved eccentricity.