A method for controlling A-shaped segregation of steel ingot. The method includes: 1) controlling a content of phosphorus in liquid steel at less than or equal to 0.005 wt. % upon tapping from an electric furnace, preventing steel slag from entering a ladle, controlling content of harmful elements at less than or equal to 100 ppm; and adding between 3 and 15 kg of calcium oxide and less than or equal to 0.5 kg of aluminum to each ton of the liquid steel; 2) pre-deoxidizing the liquid metal using vacuum carbon deoxidation; 3) de-sulfurizing, controlling content of oxygen, and controlling the content of sulfur in the liquid steel at less than or equal to 0.005 wt. %; and 4) performing vacuum degasification, controlling the total oxygen content at less than or equal to 15 ppm; and casting the steel in the presence of inert gas or in vacuum.