[Objective] Fractional slot concentrated winding (FSCW) induction motors may experience rotor eccentricity during operation, leading to the generation of air-gap flux density of non-dominant pole. This results in variations in radial electromagnetic force density, further inducing unbalanced magnetic pull (UMP), which can cause damage to the motor. To address this issue, this paper investigates the air-gap flux density, radial electromagnetic force density, and UMP of an FSCW induction motor with a 15-slot stator and an 18-slot rotor, where both the stator and rotor are FSCW. [Method] First, the causes and effects of rotor eccentricity were introduced, and the air-gap flux density expression was derived using the magnetomotive force-permeance method, followed by an analysis of its harmonic components under ideal conditions and static eccentricity fault conditions. Then, Maxwell's equations were used to obtain expressions for radial electromagnetic force density and UMP. A two-dimensional finite element model of the FSCW induction motor was developed using Ansys-Maxwell for analysis. Finally, closing the stator slot was proposed as a method to optimize the air-gap flux density and suppress UMP. [Results] Rotor eccentricity introduced additional harmonics that were multiples of three, which did not exist under ideal operating conditions, and altered the fundamental wave amplitude without changing the harmonic frequencies. When a static eccentricity fault occurred, the harmonic orders of radial electromagnetic force density shifted to ±1 of those in the ideal state, and the amplitude increased significantly. Moreover, radial electromagnetic force density and UMP increased with the eccentricity value. Compared to stator with slots, the average air-gap flux density of the motor decreased under stator with closed slots, the stator tooth harmonics were significantly reduced, and the average UMP decreased by 21.83%. [Conclusion] Rotor eccentricity is the primary cause of UMP. By adopting the stator slot closure method, the air-gap flux density is optimized, significantly reducing stator tooth harmonics and lowering radial electromagnetic force density, ultimately mitigating UMP.