Abstract: An experimental study was made on the character of oxidized round spots in electrical steel in order to determine the forming procedure of surface defects. The results showed that nice oxidized round spots could form in hot rolling cracks of Q steel and W20 steel when the temperature is over 1170℃ and 1160℃ respectively using the thermal simulator Gleeble 1500. Oxidized round spots in casting blank cracks in a heater by simulator experiment were crassitude. Desilication of the casting blank cracks were more obvious than that of hot rolling cracks by energy spectrum analysis. There was great difference in pattern, layer thickness and adjacent desilication of oxidized round spots. Such discrepancy can be set as a reference to determine the formation procedure of defects in electrical steel.