To produce different grades of steel meeting quality requirements, the carbon content must be adjusted. When the carbon content is low, this product—namely, a highly reactive carbon additive—must be added to rapidly supplement and adjust the carbon content in the molten steel. The carbon additive can be added directly or formulated into other alloys, such as manganese-carbon alloy or manganese-aluminum-carbon alloy, for addition; either way, effective carbon enhancement can be achieved. This product uses a special type of coal as raw material, which has low volatile content, high fixed carbon, and low ash content. After activation treatment with surfactants and other agents, its reactivity is significantly increased. Due to the low volatile content, it is less likely to produce smoke, reducing pollution. The low ash content and fewer impurities, combined with high fixed carbon, reduce the required dosage and lower metallurgical costs. Since carburization is an essential operation in the smelting process of many types of steel, the carburizer is an indispensable metallurgical auxiliary material in the smelting process.