Recovery of propylene from polypropylene (PP) purge stream is of great importance due to both more efficient conversion of the monomers and environmental protection. Herein, eight stable metal-organic frameworks (MOFs) with various topological structures were synthesized and their C3H6/N-2 separation performances were studied. The results indicate that CAU-1, an Al-MOF with ultramicroporous structure and amine-decorated function site, shows prominent C3H6/N-2 liming selectivity among these MOFs. The ideal adsorbed solution theory (IAST) selectivity of CAU-1 is up to 236 under ambient condition, surpassing other reported porous materials. In addition, the high recovery efficiency (>99%) obtained by breakthrough experiments, good regenerability, and high stability under harsh chemical conditions suggest the great potential of CAU-1 in practical industrial application. Our work demonstrates that the ultramicroporous structures and polar groups in CAU-1 play key roles for C3H6/N-2 separation, which provides a guideline to design and synthesize high-performance MOFs in propylene recovery from polypropylene off-gas.