A gas-liquid separation device for a vehicle includes: a housing of which an upper surface is opened and a lower surface is closed; a cover disposed on the upper surface of the housing, and the cover having an outlet disposed at a center region of the cover and an inlet disposed at a portion spaced apart from the center region; an exhaust pipe of which an upper end is connected to the outlet; a guide pipe having a cylinder shape with an upper surface opened and having a gas refrigerant flow space; a mounting cap disposed on the lower surface of the housing; and a refrigerant guider disposed on the cover inside the housing to prevent a liquid refrigerant from flowing into the gas refrigerant flow space among a refrigerant flowing into the inlet.