The utility model discloses a drainage device for a gas pipeline, which is composed of a valve body (1), a valve plug (2) making relative rotation in the valve body (1) and a drainage pipe (3) communicated with the valve plug (2). The utility model is characterized in that the valve plug (2) is provided with a radial through hole (7) and an axial through hole (8); when rotating in the valve body (1), the valve plug (2) can selectively make a drainage hole (5) or a gas hole (6) of the valve body (1) opened or closed, which makes water in a water condenser (4) discharged through the drainage pipe (3) or the condensed water pressed back to the water condenser (4) through the drainage pipe (3). Due to the adoption of such a structure, the utility model has the advantages of simple structure, convenient operation and reliability, and avoids the problem that the drainage pipe of the drainage device for a gas pipeline is easy to frost and crack in winter.