Selective capture of trace amounts of C2H2 from a C2H2/C2H4 mixture, one of the important and challenging separation processes in industry, is mainly through the energy-intensive process of solvent absorption and selective catalytic hydrogenation. Here, we reported a new supramolecular porous material, named NTU-69. It has a one-dimensional (1D) channel with an alternating cage (6.6 angstrom x 7.0 angstrom) and tube (3.3 angstrom x 3.6 angstrom), associated with reversible crystal transformation. The activated NTU-69 showed complete C2H2 capture from C2H2/C2H4 mixture, associated with high IAST selectivity (45.1, 1/99, v/v) and uptake ratio (8.1, 1 bar) at 298 K. In terms of its chemical robustness, breakthrough experiments showed cycle binary gas separation under the continuous condition without capacity loss, even in a gas feed including moisture.