The present disclosure provides a stator and winding assembly thereof. The stator includes a stator core including a tube wall and a hollow portion and a winding assembly. The winding assembly is disposed in the hollow portion and includes a first winding group and a second winding group. The first winding group includes plural winding units disposed on an inner side of the tube wall and defining an outer layer. The second winding group includes plural winding units disposed on an inner side of the outer layer and defining an inner layer. Any one of the projections of the winding units at the inner layer is partially overlapped with the projections of the two adjacent winding units at the outer layer. A number of turns of the winding units of the first winding group is equal to or greater than that of the winding units of the second winding group.