Abstract: A small-size or micro electric machine and its stator iron core. Such machine comprises rotor assembly and stator assembly installed between front & rear end covers; the stator assembly also includes the stator iron core evenly set with multiple stator slots; the bottom width of the stator slot is as 7-10 times large as the opening width of the stator slot; the shoulder width of the stator slot is as 4-7 times large as the opening width of the stator slot; the slot bottom width of the stator slot is as 1.3-2.0 times large as the slot shoulder width of the stator slot. The said small-size or micro electric machine has advantages of lower input power, higher efficiency and higher output moment of force, that is a high-efficient and energy-saving electric machine.