The stereocomplexation of poly (methyl methacrylate) (PMMA) is a unique supramolecular assembling system that has been demonstrated to be valuable in many applications. The crystallization behaviors of stereocomplex PMMA (sc-PMMA) under nanoconfinement, however, have yet to be fully understood. In this work, we fabricate sc-PMMA nanorods using anodic aluminum oxide (AAO) templates with various pore sizes to gain a fundamental understanding of sc-PMMA in confined states. A scanning electron microscope (SEM), a differential scanning calorimeter (DSC), and an X-ray diffractometer (XRD) are used to examine their morphologies, crystallization kinetics, and crystal characteristics. We discover that the crystallization kinetics of sc-PMMA inside the nanopores is significantly different from the bulk state. Also, the preferred orientation of sc-PMMA crystallites is mainly governed by the degree of spatial confinement and the polymer molecular weight. This work provides a deeper understanding of sc-PMMA under nanoconfinement and presents opportunities for the applications of supramolecular nanostructures in miniaturized devices.