A serial pump includes a pump body, a first impeller and a second impeller. A first rotor chamber, a second rotor chamber and a connecting channel are formed in the pump body. The first rotor chamber has a first outlet opening, the second rotor chamber has a second inlet opening, and the connecting channel is communicated between the first outlet opening and the second inlet opening. The first impeller is pivotally arranged in the first rotor chamber, and an outer periphery of the first impeller is arranged corresponding to the first outlet opening. The second impeller is pivotally arranged in the second rotor chamber, and a center of the second impeller is arranged corresponding to the second inlet opening. Accordingly, the first impeller and the second impeller are serially arranged.