A fluid driving device, a motor assembly and a centrifugal friction clutch thereof are provided. The centrifugal friction clutch includes: a fixing member (20) for being fixed on a rotary shaft (11) and comprising a guiding groove disposed in a radial direction of the fixing member (20) and passing through an outer circumferential surface of the fixing member (20); a centrifugal block (24) disposed in the guiding groove and slidable in the guiding groove; and a loading wheel (26) having an inner hole (261) in which the fixing member (20) is received. A gap between a wall of the inner hole (261) and the outer circumferential surface of the fixing member (20) is less than a length of the centrifugal block (24) along its sliding direction. The centrifugal friction clutch reduces vibrations at startup of the motor, thereby effectively reducing the vibrational noise. In addition, this also avoids the startup failure of the motor and effectively improves the startup performance of the motor.