The invention relates to a liquid parallel flow composite tower which is gas-liquid contact equipment used in a mass transfer process, a heat transfer process and the like in fields such as chemical industry, oil refining, petrochemical industry, pharmacy, environmental protection and the like. The composite tower comprises a tower body, wherein the tower body consists of an inner tower and an outer tower; the inner tower is sleeved in the outer tower; tower plates corresponding to cross sections of the tower body are arranged in the inner tower and the outer tower respectively; and each tower plate is provided with a down-flow system which can allow liquid on each layer of tower plates to flow in the same direction. The composite tower has the advantages of realizing large-flux mass transfer of liquid, preventing a stagnation zone from being formed on the tower plate, increasing an effective mass transfer area, enhancing treating capability, enhancing gas-liquid mass transfer averagedriving force on the tower plate and further improving the mass transfer efficiency of the tower plate.