A fan operating status monitoring system includes a detecting module to detect pulsation currents generated by the rotation of a fan, and further convert the detected pulsation currents to voltage signals, thereby allowing a differential magnifying module, a first processing module, and a control module to process the pulse wave signals in orders to measure the rotation speeds of the fan. Also, the second processing module and the control module can process the pulsation electric current signals so as to calculate the working currents of the fan, thereby expanding the measuring range of the rotation speeds of the fan, and at the same time, effectively controlling the operating status of the fan.