The invention discloses a punching die for a truncated-cone-shaped tube. The punching die comprises an upper die seat, a male die, a lower die seat and a female die, wherein two compression bars are symmetrically connected to the left and right sides of the downside of the upper die seat, vertical sliding blocks are connected to the lower ends of the compression bars, the female die is connected to the upside of the lower die seat, supporting seats are respectively arranged at the left and right sides of the female die, the supporting seats are connected onto the lower die seat, the upper sides of the supporting seats are movably connected with horizontal sliding blocks, the punching male die is connected onto the horizontal sliding blocks and is horizontally arranged, supporting plates are arranged between the female die and the supporting seats, and springs are arranged between the supporting plates and the horizontal sliding blocks. The truncated-cone-shaped tube is accurate and convenient to locate, the degree of rotational symmetry of two holes is high, deformation cannot be caused, the quality of product is high, wasting is avoided, and the production cost is reduced.