The invention relates to an integrated device used for humidifying a fuel cell, which comprises humidifying reactors, a central flow plate and tail end plates. The humidifying reactors comprise a plurality of guide plates and a plurality of diaphragms, wherein each diaphragm adopts a pervious and air isolating diaphragm, a diaphragm is arranged between any two guide plates to form a humidifying unit, the humidifying units are longitudinally overlapped to form a humidifying part, the quantity of the humidifying reactors is at least two, the two groups of humidifying reactors are arranged on both sides of the central flow plate or the front part and the rear part, the left part and the right part, or the upper part and the lower part of one side of the central flow plate, a tail end plate is arranged at the other end of each group of humidifying reactor opposite to the central flow plate, the end plated, the at least two groups of humidifying reactors and the central flow plate are integrally installed, air, hydrogen gas and cooling water respectively enter into the humidifying reactors from the end plates of the central flow plate or each humidifying reactor, and then flow out of the humidifying reactors from the end plate of each humidifying reactor or the central flow plate. Compared with the prior art, the integrated device has the advantages that the flow resistance can be reduced, the integrated device is suitable for low pressure operation, the humidifying effect can be significantly enhanced, and the like.