The present invention relates to a combustion reactor for nanopowders, a synthesis apparatus for nanopowers using the combustion reactor, and a method of controlling the synthesis apparatus. The combustion reactor for nanopowders comprises an oxidized gas supply nozzle connected to an oxidized gas tube; a gas supply unit supplying a fuel gas and a precursor gas; and a reaction nozzle forming concentricity on an inner wall of the oxidized gas supply nozzle to be connected to the gas supply unit and having an inlet opening for supplying an oxidized gas disposed at a region adjacent to a jet orifice for spraying flames. In the present invention, it is possible to precisely control the stability of flames, the uniform temperature distribution of flames and the temperature of flames that affect the properties of nanopowders, and the deposition of oxide in the combustion reactor is prevented to thus enable a continuous and uniform reaction for a long time, thereby enabling an economic and efficient synthesis of nanopowders.