This invention discloses a synchronous generator proper fractional slot sine winding. When each phase slot number of each pole is q<1, two or three layers of symmetry layout is formed after continuously winding by a specific winding with the turn ratio of 2:1 which is simpler than the unequal turn number concentric sine winding in the technology, making its phase voltage wave be of high-degree sine and the harmonic wave is lower than sine winding of unequal turn concentric double layer low harmonic magnetic potential, easy to be produced to precision high-level medium frequency AC power source to meet the need of devices with high electric performance requirement. Since q<1, the generator has small volume and light weight, and its proper fractional slot sine winding makes line voltage, phase voltage wave aberation rate smaller than 1%, and its electric property is excellent.