The invention provides a smelting method of welding rod steel H08Mn, and particularly relates to the field of ferrous metallurgy. The smelting method includes the steps of converter smelting: blast furnace molten iron is smelted in a converter to control the endpoint carbon content at 0.03-0.04%, slag-stopping tapping is carried out, pre-deoxidation is carried out by using an aluminum-manganese-iron alloy in the tapping process, and a medium-carbon manganese-iron alloy and active lime are added after tapping; and LF refining: oxygen determination and temperature measurement are performed before each time of temperature rise, an aluminum wire is fed according to a fixed oxygen value, a refining slag modifier is added, the refining temperature rise time is predicted according to a temperature measurement value, the adding amount of the refining slag modifier is increased along with the prolonging of the temperature rise time, and the slag modifier is decomposed to form CO2, the CO2 continuously escapes to form foam slag, so that air is effectively isolated, and molten steel oxygen uptake is weakened; and the oxygen content of molten steel can be controlled to be 0.0030%-0.0060%, theAls content can be controlled to be 0.0035%-0.0065%, then the molten steel is fed into a silicon-calcium line to be subjected to calcium treatment, soft blowing is conducted for 8 min-10 min, and thenthe molten steel is poured on a table. The smelting method of the welding rod steel H08Mn has the characteristics of weakening the oxygen uptake degree of the molten steel, overcoming the bubble defect of a casting blank, reducing the aluminum oxide inclusion formation amount of the molten steel, improving the castability of the molten steel, and ensuring the stable oxygen content of the molten steel.