The invention discloses a tinning method for copper or copper alloy parts. The tinning method comprises the following steps of pretreatment of the copper or the copper alloy parts, nickeling, nickeling aftertreatment, electroplating of tin, cerium, and antimony, alkali neutralization and defoaming, three-stage countercurrent washing, oxalic acid washing, the three-stage countercurrent washing, anti-tin discoloration treatment, and aftertreatment; and the parts processed by the tinning method can meet the requirement of lead-free tin welding after aging.