The invention discloses a buffer type soil gas sampling device, belonging to the technical field of soil experimental facilities. The device consists of an injector, a valve, a gas-exhausting hole, a gas-exhausting conduit, a box body, gasbags, a water seal tank and a base. As the gasbags are additionally arranged on the box body, gas pressure inside/outside the box body during a whole storing and sampling process is always maintained in a balance state after the buffer adjustment of the gasbags, the box body is prevented from outward or inward gas leakage, and the quality of gas stored in the box body is maintained; meanwhile, the difficulty that natural release of soil gas is subjected to inhibition is also overcome, the reliability of measured data for gas released by soil is enhanced.The device has the advantages of reasonable design, simplicity for operating and low cost, and can be widely applied to gathering work for greenhouse gas emission in farmland, nudation, grassland andthe like.