A board card turbo fan, comprising: a rotor housing; and a fan blade structure arranged around the rotor housing and fixed to a periphery of the rotor housing, and the fan blade structure comprising a plurality of fan blades spaced and extending inward towards a central axis of the rotor housing, wherein a cross section of the fan blade as seen in a plane that is orthogonal to the central axis of the rotor housing is a circular arc and a length of the arc is 1/8-1/6 of a circumference of a circle in which the arc is located, and wherein a first end of the arc of the fan blade is an air inlet arranged near the rotor housing and a second end of the arc of the fan blade is an air outlet facing away from the air inlet, the board card turbo fan being characterized in that a diameter of a circle in which the arc-shaped cross section of the fan blade is located is 1/10-1/6 of an outer diameter of the fan blade structure, and in that, as seen in a plane that is orthogonal to the axis of the rotor housing, an angle between - a part of a line which is tangential to the arc at the air outlet and which starts from the air outlet and extends away from the axis of the rotor housing, and - a part of a line which is tangential to the fan blade structure at the air outlet and which starts from the air outlet and extends in a rotation direction of the turbo fan, is an acute angle, so that the axis of the fan blade is close to the axis of the rotor housing, and this acute angle has a magnitude of 45 degrees. a rotor housing; and a fan blade structure arranged around the rotor housing and fixed to a periphery of the rotor housing, and the fan blade structure comprising a plurality of fan blades spaced and extending inward towards a central axis of the rotor housing, wherein a cross section of the fan blade as seen in a plane that is orthogonal to the central axis of the rotor housing is a circular arc and a length of the arc is 1/8-1/6 of a circumference of a circle in which the arc is located, and wherein a first end of the arc of the fan blade is an air inlet arranged near the rotor housing and a second end of the arc of the fan blade is an air outlet facing away from the air inlet, the board card turbo fan being characterized in that a diameter of a circle in which the arc-shaped cross section of the fan blade is located is 1/10-1/6 of an outer diameter of the fan blade structure, and in that, as seen in a plane that is orthogonal to the axis of the rotor housing, an angle between - a part of a line which is tangential to the arc at the air outlet and which starts from the air outlet and extends away from the axis of the rotor housing, and - a part of a line which is tangential to the fan blade structure at the air outlet and which starts from the air outlet and extends in a rotation direction of the turbo fan, is an acute angle, so that the axis of the fan blade is close to the axis of the rotor housing, and this acute angle has a magnitude of 45 degrees. - a part of a line which is tangential to the arc at the air outlet and which starts from the air outlet and extends away from the axis of the rotor housing, and - a part of a line which is tangential to the fan blade structure at the air outlet and which starts from the air outlet and extends in a rotation direction of the turbo fan,