Colloidal quantum dots (QDs) are promising candidates for various applications because of their unique size-dependent bandgap tunability. Owing to the nanoscale size of QDs, 40%–70% of the atoms exist on the QD surface, and the QD surface significantly affects the optical and physical properties of QDs. Thus, understanding and controlling the QD surface are very important. Here, the current understanding of the surface of IV-VI and III-V QDs will be introduced. Further, the facet-dependent surface chemistry with relating physical properties will be dicussed.