Abstract: To improve the melting effect in steelmaking process, the melting process during EAF tapping was systematically studied and solution was finally given. The area of pileup flux on surface was taken as the key parameter to describe the slagging effect and many cause factors were analyzed, tested and proved from 6 perspectivesoperator, machine, material, method, environment and measurement. The results reveal that tapping hole order and aluminium ingot addition amount play important roles in slagging effect, while not the mineralogical phases of calcium aluminate flux. Furtherly, by FactSage, the key factor influences slagging effect was finally found as lime addition amounttoo much lime piles upon the ladle slag surface. After actions taken, the slagging effect is dramatically improved, the frequency of observed pileup decreased from 80% to less than 10%.