Abstract: The stator structures including: a stator base has a plurality of stator slots and every stator slot is including two outside tunnels and an internal tunnel. The width of every outside tunnels is wider than the internal tunnel. Tow stator arrangements are provided on end of the stator base respectively. Every stator arrangement has a plurality of fixing portions and the fixing portions correspond to the outside tunnels. The thickness of every fixing portion is smaller or equal to the distance between the wall of every outside tunnel and the wall of every internal tunnel. Hence, every insulation plate occupies less space of said stator slot and the volume of every coil can be increased.