The invention discloses a mechanism for avoiding rusting of pipe connecting parts. The mechanism comprises two installing strip plates which are each shaped like a semicircular ring, supporting lugs are arranged at the two ends of each installing strip plate, the two installing strip plates are oppositely placed, and when circle centers of the two installing strip plates coincide, the two installing strip plates are connected together by enabling fasteners to penetrate through the supporting lugs which make contact with each other; and a first sealing strip is arranged on the inwards concaved surface of each installing strip plate, and the degree of a central angle corresponding to each first sealing strip is in accordance with that of a central angle corresponding to the corresponding installing strip plate. The inwards concaved surfaces of the two installing strip plates both make contact with a petroleum pipe, the installing strip plates are fixed with the fasteners, welding parts on the pipe are completely covered with the first sealing strips, the first sealing strips can deform when the installing strip plates are fixed with the fasteners, the first sealing strips can be tightly pressed on the welding parts, and the welding parts can be prevented from making contact with water vapor and sulfurous gas.