Cooling fan

A cooling fan comprising:

• a rotor hub;
• and
• a plurality of blades mounted on a periphery of the rotor hub in unequal intervals, wherein each of the plurality of blades comprises a first surface and a second surface opposite to the first surface, the first surface comprises a first side, a second side, a third side, and a fourth side, wherein each of the plurality of blades is connected to the rotor hub at the third side and the fourth side is opposite to the third side and away from the rotor hub, the first side and the second side extend from the rotor hub and are connected between the third side and the fourth side,
• wherein each of the plurality of blades is provided with a first projection plane parallel to a tangential plane of the rotor hub, the first projection plane intersects with the first surface at a first line and intersects with the second surface at a second line, the first line and the second line are connected by a first point on the first side and a second point on the second side, a profile of each of the plurality of blades being defined on the first projection plane formed by the first line, the second line, the first point, and the second point, and
• wherein the first surface of each of the plurality of blades is an irregular convex surface with a vertex and the second surface of each of the plurality of blades is an irregular concave surface with a depression point, the vertex is projected on the first projection plane to form a third point and the depression point is projected on the first projection plane to form a fourth point, an angle between a third line connecting the first point and the third point and a fourth line connecting the second point and the fourth point is defined as a first angle, the first angles of each two adjacent blades are different.