The invention discloses a method for improving deep plating capacity of electrocoppering. The method comprises the steps of A, preparing an electroplating solution including copper sulfate, sulfuric acid, sodium nitrite, 3-oxo-cyclobutylcarboxylic acid, manganese disodium EDTA trihydrate, 4-methyl-2-oxovaleric acid sodium, a brightening agent, a smoothening agent, a modifying agent and the balancewater; B, pouring the electroplating solution into an electroplating bath; and vertically arranging a circuit substrate into the electroplating bath; C, performing the first-stage electroplating; D,performing the second-stage electroplating; and E, performing the third-stage electroplating. With the adoption of the method, the shortages in the prior art can be solved; and the deep plating capacity of electrocoppering is improved.