USB fan is a miniature electric fan that is used on a desktop computer or a USB interface for a laptop computer. Computer USB port can be for external equipment provide voltage of 5 volts, current 500mA, USB Fan is using the USB interface to provide power for small fan, power banks are usually provide 5 V power, current is typically 1A and 2A, it is higher than USB electric fan operating current .so USB fan can connect power bank and make it working.