The invention discloses an anti-corrosion ultrahigh-pressure online piece hanging and taking device and a using method thereof.The anti-corrosion ultrahigh-pressure online piece hanging and taking device comprises a piece hanging device and a piece taking device.The piece hanging device comprises a welding nipple and a piece hanging sealing rod.A movable sealing rod is designed and installed in an upper hole in a sealing cavity of the piece taking device, an ultrahigh-pressure combined seal for rods is designed and installed around the upper hole in the sealing cavity and the movable sealing rod, a force application rod is installed at one outer end of the sealing cavity, the end, in the sealing cavity, of the movable sealing rod is connected with a piece taking head, the lower portion of the sealing cavity is connected with an upper connector, the upper connector is connected with a high-pressure ball valve, the high-pressure ball valve is connected with a lower connector, and a vent valve is installed on a connecting pipe of the upper connector.Due to the design of an anti-corrosion nipple in the piece hanging device, corrosion of the piece hanging device and a welding line can be effectively controlled, and thus the piece hanging device can be used for a long time.Due to the matching design of the movable sealing rod, the piece taking head, an upper sealing nipple and a pressure release sealing rod, the high-pressure ball valve can be replaced once leakage occurs, the piece hanging and taking device can be used for a long time, and the operating force in the piece hanging and taking process is small.