Disclosed herein are a method and an apparatus for preparing a metal composite powder by using gas spraying. The method of preparing a metal composite powder by using gas spraying includes introducing a matrix phase in a chamber, including a reinforcing phase in the chamber, melting the introduced matrix phase to form a melt, adding the reinforcing phase in the melt, stirring the melt with the added reinforcing phase to form a melt mixture, atomizing the melt mixture together with a gas to form a metal composite powder containing the reinforcing phase, and collecting the metal composite powder formed.