The invention discloses a highly controllable corrosion-resistant coating layer of a positive electrode grid of a lead-carbon battery, and a preparation method of a related electrode plate thereof. The corrosion-resistant coating layer is a Pb-PbO (x is less than or equal to 2) compound prepared by positive electrode electrochemical oxidization; the electrode plate is prepared from lead powder,colloidal graphite and short fibers; the Pb-PbO (x is less than or equal to 2) composite coating layer consists of multiple phases, wherein the Pb phase is connected with a lead-calcium grid; thePbO phase is connected with active materials which take lead dioxide as the main part; and Pb and PbO are tightly connected through electrochemical deposition. By virtue of the coating layer disclosed in the invention, the corrosion resistance of the grid and the connection performance between the grid and lead paste can be improved effectively, the phenomena of positive electrode grid cracking and lead paste falling off in a part of high-rate state of charge can be relieved effectively, and the overall cycle life of the battery can be prolonged; and in addition, the advantages of low cost, simple operation, high controllability and easy realization of large-scale production of electrochemical oxidization can be given into full play.