The invention belongs to the field of steel smelting, and particularly relates to a low-carbon ingot iron smelted by by-products of a titanium slag furnace and a method for smelting the low-carbon ingot iron by the by-products of the titanium slag furnace. In order to solve the problems that the carbon content of molten iron as the by-products in smelting of high titanium slag cannot be stably controlled to be below 0.01%, and the low-carbon ingot iron cannot be smelted, the invention provides the method for smelting the low-carbon ingot iron by the by-products of the titanium slag furnace. The molten iron is heated and deoxidized by an electric furnace, after iron is discharged from the electric furnace, LF deep decarbonization is carried out, after desulfurized slag is removed, the molten iron is placed in a VD furnace and then is subjected to vacuum deep decarbonization, before VD decarbonization, iron oxide scale is added and used as an oxidizing agent, after decarbonization is finished, aluminium deoxidation is carried out, carbon, silicon, manganese, phosphorus and sulfur are effectively removed from the molten iron, and the carbon content is stably controlled at relatively low level to obtain the low-carbon ingot iron. The production process is simple, requirements of equipment are not high, the quality of obtained products is good, and a mode of using the by-products of the titanium slag furnace at high added-value is provided.