The invention discloses a kind of high-cleanliness medium carbon axle steel and a preparation method thereof. The axle steel comprises the following chemical compositions in percentage by weight: 0.49-0.53% of C, 0.17-0.37% of Si, 0.65-0.80% of Mn, 0.15-0.25% of Cr, less than or equal to 0.020% of P, less than or equal to 0.010% of S, 0.020-0.060% of Al, less than or equal to 15*10-4% of O, and the balance of Fe and unavoidable impurities. The preparation method comprises the steps of electric furnace smelting, LF refining, VD vacuum degassing, blank pouring through continuous casting, and rolling, and the like. The medium carbon axle steel disclosed by the invention is stable in mechanical property and high in cleanliness, and each index is far better than standard requirements, therefore, the medium carbon axle steel has excellent comprehensive properties. In addition, micro-alloy elements are not required to be added, therefore, the preparation cost is low.