Abstract: Most of the hydrothermal simulation reactors for modeling the water-rock interaction in seafloor hydrothermal systems were designed by regulating temperature and pressure. Since the shifting of research interest to hydrothermal plume and the wide application of hydrothermal fluid sampler with fidelity recently, the new experimental simulation reactor is in high demand, which should not only keep the functions of the existing reactors, but also have the advantage to simulate the hydrothermal plume and be connected with the sampler with fidelity. We designed and tested a new experimental simulation reactor recently. The main part of this reactor is composed of two columned titanium cabins. The environmental conditions, such as temperature, pressure and fluid, can be regulated by means of the heaters, pressure devices,inputting devices and associated computers. The sides and ends of the reactor are specially designed to be able to connect with physical and chemical electrodes. Meanwhile, the China-made hydrothermal sampler with fidelity can be successfully connected with this experimental simulation reactor. The test results indicated that the experimental simulation reactor can be used to simulate the water-rock interaction and hydrothermal plume processes which have been observed under modern seafloor hydrothermal conditions.