The invention provides a multifunctional pipeline welding and assembling device. The multifunctional pipeline welding and assembling device comprises a base I, wherein a base II is connected to one end of the base I, and four stand columns are symmetrically arranged on the periphery of the base II; each stand column is formed by connecting a pipe with the diameter being 89 and a round bar with the diameter being 60 in a sleeving mode, a base plate is welded to the lower ends of the pipes of the stand columns, a lifting platform is connected to the round bars of the stand columns, and a rotary disc is arranged on the lifting platform; a hydraulic lifting column is further arranged in the middle of the base II, and an ejector rod of the hydraulic column is connected with the lifting platform. Multiple movable platforms are arranged on the base I, and the movable platforms slide on the base I. According to the multifunctional pipeline welding and assembling device, the assembling range is wide, multiple application functions can be achieved, and automatic operation is achieved; the heights of the platforms can be adjusted through automatic operation, and the labor intensity can be relieved due to automatic assembling; meanwhile, the automatic operation speed is high, assembling efficiency is improved, and economical benefits are remarkably improved; furthermore, product quality is improved.