A fuel cell system includes a circulatory device and a fuel cell module. The fuel cell module includes a membrane electrode assembly (MEA), an anode flow field plate and a heat exchange module. The anode flow field plate is disposed at a side of the MEA and has an inlet and an outlet. The heat exchange module includes a fluid-conveying unit and a heat exchange unit. At least a part of the heat exchange unit is disposed inside the fluid-conveying unit to divide the heat exchange unit into a first channel and a second channel. The first channel communicates with the circulatory device and the inlet. The second channel communicates with the circulatory device and the outlet. The circulatory device injects a portion of the liquid reactant into the anode flow field plate through the first channel. The remainder reaction solution flows into the circulatory device through the second channel.