The invention discloses a three-step pre-wetting method of through-silicon-via plating. The method comprises a step of immersing a through-silicon-via wafer of a seed copper layer in an infiltration liquid and obtaining an initial wetted wafer when the through-silicon-via wafer of the seed copper layer is completely wetted, a step of immersing the initial wetted wafer into deionized water to obtain a re-wet wafer, and a step of immersing the re-wet wafer into an plating solution such that solute in the plating solution is diffused into a through silicon via to realize the internal infiltrationof the through silicon via. According to the method, the infiltration of the through silicon via with a higher depth-diameter ratio can be achieved, a problem of seed layer falling is not caused, thecost is reduced, the process time is greatly shortened, and the efficiency is improved.