Automatic dual-source supply system

The utility model relates to an automatic double source gas supply system, which comprises a total gas output pipe, gas cylinders, a reversal valve, a controller, a first gas distributing pipe, a second gas distributing pipe, two pressure sensors for respectively detecting pressure in the two distributing pipes, a first valve and a second valve. The number of the gas cylinder is two. The output ends of the two pressure sensors are connected with the controller which controls the reversal valve. The utility model comprises an automatic switching system and two gas supply sources, one of the two gas supply sources is in use, while the other is standby for on-line redundancy. When the gas in the gas cylinder for on-line use is used up or the pressure is below the determined value, the system is switch to the stand-by gas-cylinder automatically, and the automatic gas source switching can be implemented without stopping.