Abstract: There is an electrochemical reaction in the system of metalsoil adhesion because of the interface water film. The relationship between property of soil adhesion and surface potential of plow steel was studied. The results showed that the surface potential could well demonstrate the property of adhesion of steel to soil. Under the test condition, the adhesion force and electrode potential conformed to the quadric curve. The lower surface potential was, the better the sample scored soil. Compared with other methods of measuring soil adhesion, the surface potential method has advantages of stabilizing datum and short test cycle.