Propylene (C3H6)/propane (C3H8) separation is one of the most challenging as well as most energy-intensive separation processes in the petrochemical industry. Herein we report a microporous metal-organic framework ELM-12 with appropriate channels where efficient separation of C3H6 over C3H8 is achieved via the kinetic separation effect. Time-dependent kinetic adsorption, density-functional theory calculation and breakthrough experiments collaboratively demonstrate that the considerable diffusivity difference between C3H6 and C3H8 accounts for the excellent separation performance of ELM-12. The high kinetic C3H6/C3H8 separation factor (204 at 298 K), large breakthrough time interval, and easy regeneration process of this MOF, make it a promising adsorbent for this important separation task. Furthermore, this material is highly stable under ambient condition and its production can be easily scaled up, rendering it quite favorable for practical industrial application.