Steel aluminizing is a kind of heat treatment process which infiltrates aluminum atoms into steel surfaces in chemical and physical methods to form microalloy layer, and changes surface chemical composition and characteristics of steels. Oxidation resistance, corrosion resistance and hardness of the steels could be improved by aluminizing treatment. As a simple and effective surface chemical heat treatment process, alumetizing has received attention of researchers. Current common aluminizing processes, such as hot dip aluminizing, thermal spraying aluminizing, pack cementation aluminizing and slurry aluminizing, were briefly introduced. Characteristics and disadvantages of the processes were summarized. Then, new aluminizing processes developed by the researchers, such as mechanical energy aided aluminizing, electric field aided aluminizing, chemical vapor deposition aluminizing in fluidized bed reactors and ion plating aluminizing, were introduced. Then microstructure of aluminized steels and growth mechanism of aluminized layer were discussed, oxidation resistance and corrosion resistance mechanisms of the aluminized layer were explained, and finally development trend of the aluminizing process was discussed and prospected.