Fan control system and control method thereof

The invention discloses a fan control system which comprises fans, power source conversion devices, a control device and a human-machine interface. Each power source conversion device is connected with the corresponding fan, the control device is connected with the power source conversion devices and comprises a storage module which is provided with a first database, first control data are stored in the first database, the human-machine interface is connected with the control device and is provided with a graphical interface, and second control data are set through the graphical interface of the human-machine interface and stored in the first database of the storage module to enable the control device to automatically control the fans to run at first rotating speed in a first time period and run at second rotating speed in a second time period according to the first control data and the second control data.