Abstract: In this paper the 300M steel surface is burned by quickly laser heating method to simulate the grind burn in the process of machining. Various degree of surface burn was got by adjusting different laser power, and the relation was acquired between the signal and the burn degree using the method of Barkhausen Noise method. The burn area is tested and analyzed by acid testing method.The testing result of burn indicates that Barkhausen testing method is more exact and more sensitive than acid testing method about 300M steel.