Embodiments of the present disclosure provide a method of manufacturing a metal column using 3D printing technology. The method of manufacturing a metal column includes steps of: creasing a 3D-CAD design for printing the metal column; printing the metal column; pretreating the inner surface of a channel inside the metal column at low temperature; and coating the inner surface of the channel with a stationary phase so that the metal column is capable of separating a gas mixture into components.