The present invention relates to a water removal device, method and system for gas sampling. The water removal device comprises a dehydration cup, a gas chamber, a pressure sensor, a flow sensor, a feedback control unit, a main channel and a sucking pump. The feedback control unit controls the working state of the sucking pump according to monitoring data of the pressure sensor and the flow sensor. The water removal device, method and system for gas sampling have the advantages that a double-channel gas sampling structure is adopted so that liquid water in a gas course can be removed effectively. By the adoption of an atmospheric pressure switch structure, no gas flow will pass through a second channel under normal circumstances, and the utilization of sampled gas is increased.
