Five features of slot number-phase table of cell motor were deeply discussed in this paper. Then it was derived that four constraints of cell motor with fractional slot winding and two additional constraints of cell motor with concentrated fractional slot winding. Finally，the equivalent calculation of spread factor of fractional slot motor and integral slot motor was proposed by use of the dummy motor. Because Slot numberphase table was brought in，the method proposed by this paper was convenient to carry out automatic analysis and calculation by computer.
