In order to optimize the stator slots arrangement and get high-efficiency electromagnetic scheme for the turbine generators,study on the loss taken away by the stator cooling water as well as the outlet water temperature-rise of the upper and lower layers of the stator winding was conducted.The mathematical relationship between the stator slots arrangement and the loss taken away by the stator cooling water as well as the outlet water temperature-rise of the upper and lower layers of the stator winding was established.Such key points as height of the stator bar,thickness of hollow pipe,ratio between hollow and solid bar and optimization range were proposed to be taken into account.The 660 MW generator with both water-inner-cooled stator and rotor windings was taken as an example,in which the optimized design of stator slot arrangement was described in detail.