The invention discloses a fractional pole-to-branch ratio lap winding connection method. A pole pair number of windings is an odd number, a number of slots per pole per phase is 2n, and n is a randompositive integer; each phase of winding is the same in distribution rule; in four parallel branches which form each phase of winding, each two branches are the same in distribution rule of the windings, and by regulating a coil spread of certain two pairs of poles, fractional pole-to-branch ratio wave windings of which the spreads are equal to 3*2n, 3*2n-1 and 3*2n+(2n-1) slot pitches. According to the invention, the theoretical limitation of a conventional alternating current winding is broken through; the fractional pole-to-branch ratio lap winding connection method is provided for a motor of which the pole pair number is the odd number; the conflict that a large-scaled pumped storage motor and a hydraulic turbine generator are unmatched in capacity, voltage and rotating speed is effectively solved; performance of the motor is improved; the motor is reasonable in structure, excellent in manufacturability of manufacturing and installation, simple in maintenance and reliable to operate; the technical and economical index of a power station system is improved.