Disclosed is a low-loss all-fiber high-pressure gas cavity system. The system comprises a hollow fiber, a left-end tapering processed solid fiber, a right end tapering processed solid fiber, a left end hollow fiber and solid fiber butt joint packaging module, a right end hollow fiber and solid fiber butt joint packaging module, a metal airtight chamber, a high-precision barometer and a gas flow monitoring and inflation and deflation module, wherein the left end surface of the hollow fiber is in close connection with the metal airtight chamber through sealing glue; the metal airtight chamber is in close connection with the high-precision barometer; and the metal airtight chamber is in close connection with the gas flow monitoring and inflation and deflation module. The invention further discloses an all-fiber high-pressure gas cavity realization method for performing all-fiber packaging by use of the low-loss all-fiber high-pressure gas cavity system. An all-fiber high-pressure gas cavity with such remarkable advantages as low loss, high intensity, long-term stability and the like can be realized, the method and the system have wide application prospect and important application values in such aspects as a fiber gas Raman laser and the like.