The invention relates to a small-bending-radius aviation conduit bend forming die and a forming method thereof. The small-bending-radius aviation conduit bend forming die comprises an upper die and a lower die, wherein a cavity formed after the upper die and the lower die are buckled is in a bent conduit shape, the two ends of the cavity are respectively provided with a limiting table, the limiting tables are provided with guide sleeve coaxial with the two ends of the cavity, a flexible central spindle is arranged in one guide sleeve and is connected with a low pressure piston through a connecting rod, a gasket is arranged in the other guide sleeve, the outer end face of the gasket is matched with a high pressure piston, and the low pressure piston and the high pressure piston are respectively in coaxial sliding fit with the corresponding guide sleeves. The forming die and the method thereof solve the processing difficult problem about forming of a small-bending-radius aviation conduit and realize the forming of the aviation conduit in a stable state, the phenomena of cracking, wrinkling and necking do not easily occur during forming, and a high-quality stable and efficient shaping processing method of small-bending-radius aviation conduit parts is realized.