The invention belongs to the technical field of metal processing, and particularly relates to a preparation method for large-diameter ultra-long thin-walled niobium and niobium alloy pipes. The methodspecifically comprises the steps that (1) hollow pipe blanks are prepared through high speed warm extrusion, and the inner surfaces and the outer surfaces of the pipe blanks are machined and extruded; (2) the machined pipe blanks are subjected to multi-pass power thinning spinning in a warm spinning mode, and the total warm spinning thinning rate is 70% or above; (3) semi-finished spun pipe blanks are subjected to intermediate annealing treatment, and the thin-walled pipes with the diameter being smaller than or equal to 80 mm is prepared into finished pipes through a multi-pass rolling process; (4) the thin-walled pipe with the diameter being greater than or equal to 80 mm is prepared into finished pipes through a multi-pass cold spinning process; and (5) the obtained large-diameter ultra-long thin-walled niobium and niobium alloy pipes are subjected to acid pickling and cleaned and then subjected to finished product heat treatment. The large-diameter ultra-long thin-walled niobium and niobium alloy pipes prepared through the method are even in product structure and high in comprehensive performance and additional value and have good application and popularization prospects and certain economic benefits and social benefits.