As for electrical excitation segmented-rotor flux-switching machines, the rotor pole number has great influence on the harmonic characteristics of flux-linkage and back-EMF. Firstly, the flux-switching principle of electrical excitation segmented-rotor flux-switching machines (ESFSM) was analyzed. Besides, the harmonic characteristics of flux-linkage and back-EMF were comparatively studied in theory, on the 12-tooth ESFSM models with 7 and 8 rotor poles. The result shows that the flux-linkage and back-EMF of 12/7 ESFSMs contain no even harmonics, while 12/8 ESFSMs have both even and odd harmonics. Finally, the flux-linkage and back-EMF of the 12/7 and 12/8 machines were calculated by finite element method. Basing on the fourier analysis of the flux-linkage and back-EMF, the even and odd harmonics percentage were calculated separately and the results verified the aforementioned theoretical analysis. The analysis results give the theoretical basis of the rotor pole number choice for ESFSM design.