A control device for fan state includes fan connectors arranged on a substrate and connected with at least one fan. The substrate and the fan are arranged in a case of a computer. The substrate is provided with at least one communication port, at least one microphone and a microcontroller. The communication port receives temperature signals transmitted by the computer. The microphone receives volume signals within the case. A microcontroller is electrically connected with the fan connectors, the communication port and the microphone. After the microcontroller receives the temperature signal and the volume signal, the microcontroller uses them to determine whether a value of the temperature signal or the volume signal is larger than its given value. If the answer is yes, the microcontroller controls a rotational speed of the fan, turns off the fan, or provides control items displayed on a screen of the computer to choose.