The invention relates to a method for smelting high-grade flaw detection steel. The method comprises the steps of electric furnace melting, refining, vacuum treatment, casting and rolling, wherein under the condition of electric furnace melting, molten steel is subjected to preliminary deoxidation until the oxygen content is between 100 and 300 ppm, and the ladle temperature is controlled to be between 1,560 and 1,650 DEG C; under the condition of refining, an aluminum wire is fed according to the refining oxygen determination value, a grain refining agent is added into the molten steel, and argon blowing is performed for at least 3 minutes; the molten steel is refined until the oxygen content is between 20 and 30 ppm and the S content is not more than 0.015 percent, the temperature is controlled to be between 1,650 and 1,660 DEG C, and the molten steel is subjected to slag-off treatment; vacuum pre-molten slag is added into a ladle before vacuum treatment, and maintained for at least 20 minutes at a vacuum degree of not more than 0.5 torr; and low-carbon composite slag powder with the carbon content of not more than 6.0 percent is adopted for casting under the protection of inert gas. The method is simple and convenient to operate, is a novel approach for preparing the high-grade ultrasonic flaw detection steel, makes smelting by utilization of steel scrap raw materials become possible by controlling the factors influencing the flaw detection grade of ingots, realizes optimum resource utilization, and widens the variety of electric furnace steel.