An efficient propylene/propane separation is a very critical process for saving the cost of energy in the petrochemical industry. For separation based on the pressure-swing adsorption process, we have screened ~1 million crystal structures in the Cambridge Structural Database and Inorganic Crystal Structural Database with descriptors such as the surface area of N2, accessible surface area of propane, and pore limiting diameter. Next, grand canonical Monte-Carlo simulations have been performed to investigate the selectivities and working capacities of propylene/propane under experimental process conditions. Our simulations reveal that the selectivity and the working capacity have a trade-off relationship. To increase the working capacity of propylene, porous materials with high largest cavity diameters (LCDs) and low propylene binding energies (Qst) should be considered; conversely, for a high selectivity, porous materials with low LCDs and high propylene Qst should be considered, which leads to a trade-off between the selectivity and working capacity. In addition, for the design of novel porous materials with a high selectivity, we propose a porous material that includes elements with a high crossover distance in their Lennard-Jones potentials for propylene/propane such as In, Te, Al, and I, along with the low LCD stipulation.