Central gas supply system and method for large open caisson mud suction sinking construction

The invention relates to the field of open caisson construction, in particular to a central gas supply system and method for large open caisson mud suction sinking construction. The central gas supply system comprises two sets of gas storage tanks; each set comprises multiple gas storage tanks; each gas storage tank is connected with two air compressors; each set of gas storage tanks is connected with a blast main; a gas storage tank valve is arranged between each gas storage tank and the corresponding blast main; the two blast mains are arranged along the top of the lateral wall of an open caisson, and the ends on the top of the lateral wall are communicated to form a closed loop; each blast main is connected with multiple branch air pipes; each branch air pipe is connected with a mud suction machine. When a certain gas storage tank breaks down or the corresponding air compressor breaks down, the corresponding gas storage tank valve is closed, then maintenance is conducted, and the central gas supply system works normally. The stability of the whole gas supply system is ensured, and the whole open caisson mud suction efficiency is prevented from being affected.