The invention relates to a low-alloy steel electrode with ultra-low hydrogen alkalinity and a preparing method thereof. The steel electrode comprises a core wire and a coating. The core wire is the H08E core wire, the coating is low-hydrogen design with high alkalinity, and the component comprises marble, fluorite, silica powder, titanium dioxide, ferrotitanium, silicon iron, manganese metal, ferromolybdenum, nickel powder, boron iron powder, yttrium oxide and sodium carbonate. Compared with the prior art, the welding process is excellent, in the welding process, the electric arc is stable, basically, no splashing exists, the slag detachability is good, a molten pool is clear, the welding line forming is attractive, the steel electrode is excellent in operation, and the excellent depositedmetal, impact toughness and the like are achieved.