A fan to be used as a relay node comprises male and female connect ports, a transmission wire set connecting the male and female connect ports, a power acquisition unit, and a signal processing unit. The male connect port is connected to a control source for receiving a working power and a control signal. The female connect port is selectively connectable to the male connect port of another fan to allow the fan electrically connect with another fan. The power acquisition unit is connected in parallel with the transmission wire set for extracting the working power to supply to a driving unit. The signal processing unit is connected to the transmission wire set to obtain and output the control signal to the driving unit, and acts as a relay node to output the control signal to the female connect port, so that the other fan can be controlled.