A fuel cartridge includes a plurality of chambers and a plurality of supply devices. Each of the chambers is capable of storing a first reactant. The supply devices are respectively corresponding to the chambers; and each of the supply devices is capable of supplying a second reactant to the corresponding chamber so that the second reactant reacts with the first reactant in the corresponding chamber to generate hydrogen gas. In addition, a fuel cell system using the fuel cartridge and a power management method thereof are also provided.