Under the current background of carbon peaking and carbon neutrality, the iron and steel industry undertakes the arduous task of carbon reduction, and it also provides an opportunity for the iron and steel industry to transform and upgrade towards green and environmentally friendly low-carbon metallurgy. In the non-blast furnace iron-making process, carbon will affect the physical properties of molten iron and the reaction of the slag-iron interface. For the developing hydrogen metallurgy process, the presence of hydrogen will also affect the behavior of carbon in iron. The traditional blast furnace smelting process is started to firstly summarize the experimental research methods of molten iron surface tension, slag-iron interfacial tension, molten iron viscosity and melting temperature, and to summarize and analyze the effect of carbon content on molten iron surface tension, slag-iron interfacial tension, molten iron viscosity and melting temperature. The results show that the carbon content has no direct relationship with the surface tension of molten iron, but the carbon content will affect the adsorption of surface active elements such as oxygen and sulfur on the surface of molten iron, thereby affecting the surface tension; the interfacial tension of slag iron is related to the carbon content, temperature, slag composition, and the distribution of oxygen at the slag iron interface; with the decrease of temperature, the viscosity of molten iron increases first, and when the temperature decreases below the melting point of molten iron, the viscosity decreases rapidly, and with the increase of carbon content, the temperature at the turning point decreases; the molten temperature of molten iron shows a trend of decreasing first and then increasing. The research results can provide references for iron workers to understand the influencing factors of the physical properties of iron-based melts, and provide theoretical support for the separation of slag and iron.