The invention relates to a steel slag radiation shield concrete and a preparation method thereof. The steel slag radiation shield concrete comprises the following components in parts by weight: 1 part of cement, 0.4-0.5 part of water, 4-8 parts of steel slag sand, 0.01-0.03 part of water reducing agent, 0.01-2 parts of barite and 0.01-0.03 part of colemanite, wherein the steel slag sand comprises two kinds of steel slag sand with the particle size ranges of 0-5mm and 5-25mm according to the proportion of 1-3:1-3, and the f.CaO content of the steel slag sand is less than or equal to 3%; the water reducing agent is selected from an FDN water reducing agent and a polycarboxylate water reducing agent; and the apparent density of the steel slag radiation shield concrete is greater than 2900kg/m<3>. The steel slag radiation shield concrete of the invention has good compactness, large apparent density and high strength and meets the requirements of the radiation shield concrete; the invention changes waste steel slag into valuable resources, reduces the environment pollution, simultaneously lowers the consumption of mineral materials, and saves natural resources; and in addition, the steel slag used in the invention has abundant resources, low price and obvious economic benefit.