NOVELTY - The system comprises: an input reactant injecting device for injecting a mixture of lignocellulosic biomass received from bio-oil and water as a reactant; a pre-heating device for pre-heating the reactant; a vertical reaction apparatus for performing a catalytic reaction on the preheated reactant in a supercritical water condition to produce a synthesis gas; and post-processing unit for removing a foreign substance in the produced synthetic gas. The reactant injecting device comprises a water storage tank installed in a lower part, a cylindrical input device, and a high pressure pump.    USE - The system is useful for reforming bio-oil in a supercritical water condition (claimed).    ADVANTAGE - The system is capable of rapidly and continuously reforming the bio-oil.    DETAILED DESCRIPTION - The system comprises: an input reactant injecting device for injecting a mixture of lignocellulosic biomass received from bio-oil and water as a reactant; a pre-heating device pre-heating the reactant; a vertical reaction apparatus performing a catalytic reaction on the preheated reactant in a supercritical water condition to produce a synthesis gas; and post-processing unit removing a foreign substance in the produced synthetic gas. The reactant injecting device comprises a water storage tank installed in a lower part, a cylindrical input device, and a high pressure pump. The cylindrical input device comprises a cylindrical body. An inner portion of the cylindrical input device is segmented by a reactant chamber and a water chamber with a piston. The high pressure pump transfers the high pressure water to the water chamber through the cylindrical input device. Air outlets are installed at the cylindrical input device. On-off valves are arranged in the air outlets. The piston pressurizes a cylinder inner space connected with the reactant chamber and the water chamber. A reactant supply tube supplies the reactant to the vertical reaction apparatus within the reactant chamber. A reactant injection pipe is piped to the cylindrical input device. A water pouring tube injects the water into the water chamber. An inner heater is arranged inside the preheating device and heats the reactant. An outside heater heats the reactant and is installed at an outer side surface of the preheating device. A catalyst support is protruded to a central axis along an inner periphery in the vertical reaction apparatus. A disk filter prevents the outflow of a catalyst. A catalyst layer is arranged at an upper part of a metal net of the reaction chamber. A solid material reservoir stores the solid material and is installed in a lower part of the vertical reaction apparatus. A thermocouple is arranged in the reaction chamber to measure the preheating temperature and reaction temperature of the reactant. A synthetic gas flow meter measures a flow rate of the synthetic gas. A post pressure controller decompresses the pressure of a product. A flash chamber separates a depressurized product. A filter filters the solid material from the product at an ambient pressure. A heat exchanger exchanges the reaction heat produced in the horizontal reaction apparatus. The vertical reaction apparatus composes a preheat chamber and the reaction chamber, each of which comprises preheater and a reaction tube. An inner part projecting part of the connection part is connected to the catalyst support in which the metal net is placed. An INDEPENDENT CLAIM is included for a method for reforming bio-oil in a supercritical water condition.