The invention provides a temperature compensation method for molten steel in a steel ladle. The method comprises the steps of take the measures of slag stopping when converter is carried out, and when steel is ladled controlling the temperature of the inner wall of the steel ladle between 900 and 1000 DEG C; after converter tapping is finished, according to the proportion of 3 to 7kg per ton of steel adding a temperature raising agent which is prepared by evenly dry-mixing industrial aluminum powder or aluminum granule, crushed metallurgical waste iron scale and metallurgical lime screening material powder to the top of the molten steel in the steel ladle, and covering the steel ladle with an insulating cover. The method provided by the invention which is free from the change of the steel ladle and the equipment, additional facilities, more investment, and the change of the structure of the steel ladle modifies the physical property of the slag at the top of the steel ladle by adding the temperature raising agent consisting of metallurgical wastes to the molten steel, and compensates for the temperature loss of the molten steel by using the chemical heat generated by the reaction, thereby the temperature drop of the molten steel can reduce by 20.1 DEG C. The method provided by the invention is characterized by simple process, easy operation, low investment, quick effect, low cost and less energy.