A compact battery unit of refillable aluminum-air battery with concurrent hydrogen utilization system comprises a stack core, an electrolyte circulation system, an air circulation system, a hydrogen fuel battery and hydrogen storage facility. The stack core is assembled by one or more cylindrical cells, a cell base, a cell house, an electrolyte cover, an air cover, a hydrogen cover, an electrolyte outlet sink, a electrolyte inlet chamber, soft pipes and a vibrator. The cylindrical cell is further assembled from a cylindrical cathode and a cylindrical anode. The cylindrical cathode comprises a multi-layer cathode electrode, a support frame and a cathode electric connector. And the cylindrical anode comprises an electric-conductive frame, anode membrane meshes, granular aluminia etc. Strong alkaline electrolyte, such as NaOH, is used to make it possible to mechanically recharge the aluminum-air battery.