The invention relates to a lithium-rich electrode plate of a lithium-ion battery and a preparation method thereof. The electrode plate includes a collector; a film containing an active material and forming on the collector, and forming an elementary electrode plate together with the collector; and a porous lithium sheet covering on the film, so that a resulting capacity of the porous lithium sheet matches a planned lithium-supplemental capacity to an anode of a lithium-ion battery. The electrode plate can accurately control lithium supplemental quantity to the anode, improve lithium-supplemental uniformity, improve the first coulombic efficiency, energy density, and electrochemical performance of the battery, and decrease deformation of the cell. Furthermore, the method can be performed simply and the cost thereof is low.