A stator assembly, comprising: a stator core, and a winding, wherein the stator core comprises teeth (2; 4; 8; 9) and a yoke (1; 3), and the yoke (1; 3) comprises an inner circumferential surface (11; 31) and an outer circumferential surface (12; 32), and the teeth (2; 4; 8; 9) are arranged and distributed along the inner circumferential surface (11; 31) or the outer circumferential surface (12; 32) of the yoke (1; 3), wherein the stator core is formed by stacked silicon steel sheets, and each of the teeth (2; 4; 8; 9) comprises a neck (21; 41; 5; 81) and a tip (22; 42; 6; 82), and two ends of the neck (21; 41; 5; 81) are respectively connected to the yoke (1; 3) and the tip (22; 42; 6; 82), wherein the neck (21; 41; 5; 81) provides support for winding of the winding, and the neck (21; 41; 5; 81) comprises a first stacking portion (211; 4111; 531; 8111), a second stacking portion (212; 4112; 532; 8112), a first plane portion (213; 4113; 533; 8113) and a second plane portion (214; 4114; 534; 8114), and the first stacking portion (211; 4111; 531; 8111) and the second stacking portion (212; 4112; 532; 8112) are arranged opposite to each other, the first plane portion (213; 4113; 533; 8113) and the second plane portion (214; 4114; 534; 8114) are arranged opposite to each other, and the first stacking portion (211; 4111; 531; 8111) and the second stacking portion (212; 4112; 532; 8112) are formed by stacking silicon steel sheets of the neck (21; 41; 5; 81), wherein in a stacking direction of the neck (21; 41; 5; 81), the first plane portion (213; 4113; 533; 8113) and the second plane portion (214; 4114; 534; 8114) are outer surfaces of silicon steel sheets located at two axial ends of the neck (21; 41; 5; 81); characterized in that in the stacking direction of the silicon steel sheets of the neck (21; 41; 5; 81), and from the first plane portion (213; 4113; 533; 8113) and/or the second plane portion (214; 4114; 534; 8114) to the middle of the winding portion of the neck (411; 53) in a height direction, the widths of the silicon steel sheets gradually increase to allow the first stacking portion and the second stacking portion (212; 4112; 532; 8112) to be in an arc-like shape; wherein a furthest distance from the first stacking portion (211; 4111; 531; 8111) to the second stacking portion (212; 4112; 532; 8112) is a first distance, a distance between the first plane portion (213; 4113; 533; 8113) and the second plane portion (214; 4114; 534; 8114) is a second distance, and the ratio of the first distance to the second distance is greater than or equal to 1/2 and smaller than or equal to 1. a stator core, and a winding, wherein the stator core comprises teeth (2; 4; 8; 9) and a yoke (1; 3), and the yoke (1; 3) comprises an inner circumferential surface (11; 31) and an outer circumferential surface (12; 32), and the teeth (2; 4; 8; 9) are arranged and distributed along the inner circumferential surface (11; 31) or the outer circumferential surface (12; 32) of the yoke (1; 3), wherein the stator core is formed by stacked silicon steel sheets, and each of the teeth (2; 4; 8; 9) comprises a neck (21; 41; 5; 81) and a tip (22; 42; 6; 82), and two ends of the neck (21; 41; 5; 81) are respectively connected to the yoke (1; 3) and the tip (22; 42; 6; 82), wherein the neck (21; 41; 5; 81) provides support for winding of the winding, and the neck (21; 41; 5; 81) comprises a first stacking portion (211; 4111; 531; 8111), a second stacking portion (212; 4112; 532; 8112), a first plane portion (213; 4113; 533; 8113) and a second plane portion (214; 4114; 534; 8114), and the first stacking portion (211; 4111; 531; 8111) and the second stacking portion (212; 4112; 532; 8112) are arranged opposite to each other, the first plane portion (213; 4113; 533; 8113) and the second plane portion (214; 4114; 534; 8114) are arranged opposite to each other, and the first stacking portion (211; 4111; 531; 8111) and the second stacking portion (212; 4112; 532; 8112) are formed by stacking silicon steel sheets of the neck (21; 41; 5; 81), wherein in a stacking direction of the neck (21; 41; 5; 81), the first plane portion (213; 4113; 533; 8113) and the second plane portion (214; 4114; 534; 8114) are outer surfaces of silicon steel sheets located at two axial ends of the neck (21; 41; 5; 81); characterized in that in the stacking direction of the silicon steel sheets of the neck (21; 41; 5; 81), and from the first plane portion (213; 4113; 533; 8113) and/or the second plane portion (214; 4114; 534; 8114) to the middle of the winding portion of the neck (411; 53) in a height direction, the widths of the silicon steel sheets gradually increase to allow the first stacking portion and the second stacking portion (212; 4112; 532; 8112) to be in an arc-like shape; wherein a furthest distance from the first stacking portion (211; 4111; 531; 8111) to the second stacking portion (212; 4112; 532; 8112) is a first distance, a distance between the first plane portion (213; 4113; 533; 8113) and the second plane portion (214; 4114; 534; 8114) is a second distance, and the ratio of the first distance to the second distance is greater than or equal to 1/2 and smaller than or equal to 1.