The invention discloses a device and a method for collecting leakage natural gas in submarine cold seepage regions. The device comprises a gas collecting chamber, a collector, a buoyancy apparatus and a gas storage tank. The gas collecting chamber, the collector and the buoyancy apparatus are sequentially coaxially connected with one another by a guide buoy chain from bottom to top, the buoyancy apparatus is communicated with the gas storage tank, and the collector can ascend or descend along the guide buoy chain and further can be connected with the gas collecting chamber and the buoyancy apparatus or can be disconnected from the gas collecting chamber and the buoyancy apparatus. The device and the method for collecting the leakage natural gas in the submarine cold seepage regions have the advantages that the leakage natural gas in the submarine cold seepage regions can be collected by the aid of influence of submarine temperature and pressure variation on states of the leakage natural gas in the submarine cold seepage regions; the device for collecting the leakage natural gas in the submarine cold seepage regions is high in collection efficiency, and accordingly the device and the method have important economic significance.