The invention discloses an underwater vertical connector sealing component replacing tool. The underwater vertical connector sealing component replacing tool comprises an annular shell, wherein an elastic ring is arranged at an upper open end of the annular shell; the elastic ring extends out of the annular shell; at least three vertical plug pins are arranged inside the annular wall of the annular shell; each vertical plug pin comprises a long-diameter part and a short-diameter part; transverse plug pins with the number equal to that of the vertical plug pins are arranged inside the annular wall in the annular shell; grooves are formed in the transverse plug pins; lifting hooks are arranged on the end parts, near the central end of the annular shell, of the transverse plug pins; transverse springs are arranged on transverse plug pins; along with downward movement of the vertical plug pins, when the grooves on the transverse plug pins are matched with the short-diameter parts of the vertical plug pins, the transverse springs rebound to generate a restoring force; and the transverse plug pins move in a direction far away from the center of the annular shell under the action of the restoring force. The underwater vertical connector sealing component replacing tool is compact and exquisite in structure, purely mechanical in matching, free of a hydraulic structure, small in overall size and convenient to operate.