Abstract: The nanocrystalline Cu-Al alloy was synthesized by flow-levitation method. The analysis based on TEM and XRD, were earned out in order to evaluate the size and composition of the alloy phase of powder. Results show that the nanocrystalline intermetallic compound Cu₄Al is formed when evaporating Cu-Al master alloy is 3.6:1 （at%）, grain size of the Cu₄Al powders is about 30-50nm. Moreover, the procedure of nanocrystalline intermetallic compound Cu₄Al formation during gas evaporation process is discussed.