The invention discloses a gas tunnel control method and a system thereof and belongs to the field of tunnel construction. The control method comprises a first step of advance geological forecast, a second step of construction ventilation and a third step of gas detection. A gas monitoring system comprises gas sensors, a fan starting and shutdown sensor and a warning device, wherein the gas sensors are respectively arranged on an inner tunnel face of a tunnel, a secondary lining trolley and a return air place; and the fan starting and shutdown sensor is arranged on a fan. The fan starting and shutdown sensor monitors stop signals of the fan and is connected with a tunnel power supply line to control disconnection and connection of the tunnel power supply line, the gas sensors monitor the concentration of gas in the tunnel, are respectively connected with the tunnel power supply line to control disconnection and connection of the tunnel power supply line and are electrically connected with the warning device to control the warning device to be on and off. The gas tunnel control method and the system are targeted, comprehensive and strict and aims to deal with specific conditions of the gas tunnel.