Abstract: This paper has determned melting rates of mild steel wire, stainless steel wire and aluminum alloy wire through many experiments.With the method combining semi-theory with experiment, measurment and calculation are done to determine the propotion of that caused by the abide heating and ohmic heating in the melting rate og the above wires.Further more,experiment was carried out to study the action and influence of shielding gas.The paper also determines several constants convering the semi-theory formula describing melting rate of all dinds materials,and analyses the formula’s practicality.