A nanopowders synthesis apparatus includes a reaction chamber, the reaction chamber having a top portion, a bottom portion opposite to the top portion, a sidewall adjoining the top and the bottom portion, and an inlet and an outlet; a first sprayer formed in the sidewall configured for spraying a first reactant into the reaction chamber therefrom; and a second sprayer formed in the bottom portion configured for spraying a second reactant into the reaction chamber therefrom. The inlet formed in the top portion configured for injecting a liquid medium, and the outlet formed in the bottom portion configured for releasing the liquid medium. A nanopowders synthesis method is also provided.