Abstract: In view of the changes of steelmaking process and steelmaking cost after adding pig iron block to the 65 t converter of Masteel to improve the scrap ratio, the thermal effect of pig iron block and scrap was calculated, and it was concluded that the scrap cooling effect was about 1/4 of the surplus heat of exothermic oxidation after melting the same amount of pig iron block. Therefore, on the basis of meeting the heat balance of the converter, the industrial test of the smelting process of adding pig iron block to the converter was carried out, and the influence of increasing the scrap ratio by using the pig iron block heat compensation process on the converter blowing process was studied. The steelmaking cost and comprehensive economic benefits under different loading systems were compared and analyzed to determine the optimal loading system. The results show that with the increase of the proportion of pig iron, the temperature drop of molten pool increases. When the proportion of pig iron is more than 6%, the temperature drop of molten pool exceeds 100 ℃, which has an adverse impact on the temperature rise of the molten pool and the end-point control. The end-point phosphorus hit rate of converter decreases from 95.71% to 89.42%, and the oxygen consumption increases from 49.40 m³/t to 51.91 m³/t. When the loading system is 80.85% molten iron +17.27% scrap+1.88% pig iron block, the comprehensive economic benefit per ton of steel is the highest, and the scrap ratio increases from 17.21% to 19.15%.