The invention discloses a high-strength atmospheric-corrosion-resistant steel bar and a preparation method thereof, and belongs to the technical field of steel preparation. According to the preparation method, the problems that in the prior art, high-priced ore concentrates are adopted in the alloy preparation process, iron is wasted in the preparation process and the whole preparation process ofthe high-strength atmospheric-corrosion-resistant steel bar is tedious and high in cost are solved. The preparation method comprises the following steps that 1, marine sand ore, copper slag and coal powder are pretreated and uniformly mixed, so that a raw material mixture is obtained; 2, hydrated lime flux and a syrup additive are added into the raw material mixture, so that a to-be-reduced material is obtained; 3, the to-be-reduced material is pressed into a ball and dried, so that a pellet is obtained; 4, reduction and posttreatment are carried out on the pellet, so that a vanadium-titanium-copper-iron alloy is obtained; and 5, molten steel smelting is carried out through a converter or an electric furnace, the vanadium-titanium-copper-iron alloy and ferrophosphorus are added in the tapping process of molten steel, refining, continuous casting and hot rolling are carried out, so that the high-strength atmospheric-corrosion-resistant steel bar is obtained. The preparation method can be used for preparing the high-strength atmospheric-corrosion-resistant steel bar.