The invention discloses a method for large-calibre aluminium-alloy pipeline no-liner tungsten electrode argon arc one-side welding both-side formation, comprising the following steps of: assembling of groove angle and clearance, grinding of tungsten electrode, cleaning before welding, adjusting welding process parameters, tack welding, and welding of a bottom coating, a filling layer and a covering layer. The pipe is horizontally fixed and the position is marked by hour; the welding sequence is left half-ring and right half-ring; each half-ring comprises overhead welding, vertical position welding and downhand welding; the welding is started at a position where L is equal to 5-10mm close to six of the overhead welding; the vertical position welding is then carried out; finally, the front half-ring is ended at 12 of the downhand welding; before the rear half-ring starts welding, the connection is grinded as a slope; the welding seam formed by the connection and the front half-ring welding position is overlapped by 3-5mm; the welding of the rear half-ring is started from 6 of the overhead welding and ended at 12 of the downhand welding through the vertical position welding; the welding is carried out by a continuous feeding method. The surface of the welding seam of the method has no pores or cracks, is completely welded and beautiful, and has good internal and external forming; by the non-destructive testing, the first-time qualification rate achieves 100%, the welding seam achieves the class-1 quality, the construction procedures are reduced, and the construction cost is reduced.