The invention relates to the field of tunnel construction, in particular to a large-span loess tunnel upper bench CD construction method. The large-span loess tunnel upper bench CD construction methodcan ensure the construction safety and the engineering quality, mutual interference of construction of steps is small, and the construction progress is high. The large-span loess tunnel upper bench CD construction method comprises the steps that (1) an arch part of an existing pilot tunnel in the left side is excavated; (2) existing core soil is excavated; (3) an arch part of a following pilot tunnel in the right side is excavated; (4) following pilot tunnel core soil is excavated; (5) an existing pilot tunnel side wall is excavated; (6) a following pilot tunnel side wall is excavated; (7) aninverted arch is excavated.