The disclosure provides a nozzle for combustion and reforming reaction including a fuel pipe, a reformer, an activation pipe, an activation catalyst, and a reformation catalyst. The fuel pipe includes an annular wall and an end wall connected to an end of the annular wall. The fuel pipe has at least one vent hole penetrating through the annular wall and at least one outlet penetrating through the end wall. The reformer is disposed in the fuel pipe. The activation pipe is disposed in the fuel pipe and disposed through the reformer. A distance between the activation pipe and the outlet is larger than a distance between the vent hole and the outlet. The activation catalyst is arranged in the activation pipe. The reformation catalyst is arranged in the reformer and located outside the activation pipe. The disclosure also provides a combustor and a fuel cell system having the nozzle.