A method for producing metal oxide nanocrystals, according to the embodiment of the present invention, includes: continuously flowing, into a continuous flow path, one or a plurality of nanocrystal precursor solutions each comprising one or more nanocrystal precursors dissolved in a non-polar solvent; directing a segmenting gas into the continuous flow path to create a segmented reaction flow; flowing the segmented reaction flow into a thermal processor; heating the segmented reaction flow in the thermal processor to create a product flow; and collecting metal oxide nanocrystals from the product flow.