The present invention discloses a method for smelting rust preventing and wear resistant alloy on the surface of a steel rail. The position needing alloy smelting on the surface of the steel rail head is heated by supersonic frequency or medium frequency induction-heating equipment, the induction heater is arranged above the position needing alloy smelting on the surface of the steel rail head, and the preheating temperature is 290-450 DEG C; the alloy is smelted on the surface of the steel rail head by using plasma smelting or arc welding smelting, when the preheating temperature is 290-450 DEG C, and the welding gun of plasma build up welding or arc welding equipment is moved to the position needing alloy smelting, the alloy powder, the alloy electrode or the alloy welding wire are automatically smelted; the railroad steel rail adopting the present invention can ensure that the train wheels and the rust preventing and wear resistant alloy layer are always in a contacting and compacting state, thereby the rail circuit works normally, and the white light zone phenomenon is completely eliminated; the cracking and breaking phenomena of the steel rail do not occur, the smelted alloy has good rust preventing and wear resistant properties, high bonding strength with the steel rail, and long service life.