Mechanical energy aided aluminizing process was applied on 1Cr18Ni9 stainless steel. Aluminized layer of 30-180μm was obtained after heat preservation for 3h at low temperature of 650-700°C. The microstructure of aluminized layer and the mechanical energy aided aluminizing mechanism were analyzed. Aluminized layer consists of three major phase, pure Al layer, Me2Al7phase layer and Me2Al5 & MeAl two-phase layer, respectively. Me2Al5 and MeAl of the two-phase layer have different Ni content, with the precipitated phase of chromium-silicon compounds.