The invention discloses a non-span-reducing construction method for a super-large-section loess tunnel close to an underlying operating railway. Firstly, the influence range of the super-large-section loess tunnel passing under the operating railway is divided into three support level areas-I area, II area and III area. , and then carry out the construction of the pipe shed studio, the construction of the pipe shed, the backfilling of the pipe shed work room, and the reinforcement of the small conduit in advance, and finally adopt the three-step + two-step temporary inverted arch method to excavate and support the cave body. The invention is used to safely and quickly pass under the operating railway area, shorten the construction period, reduce the cost input, achieve the combination of safety, economy and rationality, and provide the same type of super-large section loess tunnels for the construction of the same type of super-large section loess tunnels close to the under-passing operating railway. Based on the reference, the construction efficiency of super-large-section loess tunnels passing under the operating railway can be further improved, and the construction safety risk can be reduced.