The invention relates to a support device for pipeline inner wall and a construction method thereof. The support device for the pipeline inner wall comprises a support, at least two supporting arms, locating tabs, and adhesive discs. A first supporting arm is spliced by four orthogonal steel pipes to form a cross-shaped first supporting arm, the upper portion of the first supporting arm is provided with the support, and four end portions of the first supporting arm is provided with a round-shaped gap which is separately connected with a second supporting arm by the locating tabs. Each locatingtab is a circular ring with two handles, the bottom of the locating tabs is provided with a circle of convex plate, the locating tabs are arranged on the round-shaped gap of the first supporting armand is hinged with the first supporting arm by the round-shaped gap, and the second supporting arm is located in the round-shaped of the first supporting arm and is connected with the inner ring of the circular ring of the locating tabs; and the other end of the second supporting arm is hinged with the corresponding adhesive disc. According to support device for the pipeline inner wall, major diameter pipeline without damaged installation can be achieved, the inner wall of the pipeline is integrated, working procedure is reduced, human input is reduced, cost is saved, and construction time isreduced.