Abstract: A reluctance method of measuring corrosion rate, which is based on the measurement of metal loss through the change of the reluctance of the probe is introduced and used to study the corrosion of carbon steel in tap water with different aeration and in 0.5?mol·L ^-1 HCl with and without the presence of PAAC and Tw-20.The method is nondestructive, rapid,sensitive in measurement of corrosion rate and can also be used to study the adsorption process of inhibitors on the surface of metal materials.A new method, the reluctance method allied with electrochemical method is given, which can properly monitor the relative corrosion rate of metal materials with a common reluctance probe under the condition of cathodic protection.