The invention belongs to the field of wire production, and particularly relates to a movable welding point metal ion re-plating machine and a re-plating method thereof. The machine comprises a car body. A plating solution tank is arranged on the table face of the car body. Anode plates are put in a left tank cavity and a right tank cavity, and the anode plates are connected to the positive pole of a power source through an anode wire. The machine further comprises a turnover plate, and the top end of the turnover plate is fixedly connected with a re-plating plate. Two bosses used for straightening and locating a to-be-re-plated copper wire are arranged at the top end of the re-plating plate in a convex manner. The re-plating plate is connected to the negative pole of the power source through a cathode wire. The machine has the beneficial effects of being simple in structure, flexible and convenient to use and reliable and stable in work, the production cost is ensured, and meanwhile the product quality of the tin-plated copper wire can be effectively guaranteed. The method comprises the following steps that tin plating master batch welding and connector grinding treatment are carried out to obtain the to-be-re-plated copper wire; and then oil removal and re-plating operation are carried out. The efficiency and reliability of the tin plating process can be effectively ensured through the above method.