Gas filling system and gas filling method

The invention discloses a gas filling system and a gas filling method, and relates to the technical field of carbon dioxide capture and transportation. The gas filling system comprises a storage tank, a to-be-filled tank, an intermediate tank, a first pipe, a second pipe, a vacuumizing assembly and a pressure measuring instrument, the storage tank is connected with an exhaust pipe provided with a first valve, the to-be-filled tank is connected with a gas inlet pipe provided with a second valve, the intermediate tank is provided with a transfer cavity communicated with the first pipe and the second pipe, and the first pipe and the second pipe are communicated with the transfer cavity. The other end of the first pipe is connected with the exhaust pipe, the other end of the second pipe is connected with the air inlet pipe, the vacuumizing assembly is arranged in the intermediate tank and used for vacuumizing the transfer cavity, and the pressure measuring instrument is arranged in the intermediate tank and used