Abstract: The cathodic protecion of conductive coating of constraint cell voltage without reference electrodes has got rid of the grephytic referencial electrodes used in constant potential method. Thus overcoming the affects on cathodic protection potentials caused by unstable potentials of grephytic electrodes. If apptied, when there is uneven state between wetness and driness, this technique can self— regulate the polarization current density--i_n required by each area (wet or dry) thus enabling the protection potentials of E Constraint Cell Voltage and q_n remain unchanged with the potentials distributing evenly and high protection efficieney is thus maintained.Compared with constant potential method, this technique has such advantages as being convenient in maintenance, reliable in operation.It can be widely used in the environments with technical atmosphere and marine atomosphere (wet and spleshing), therefore convenient to spread.