Dynamic covalent chemistry (DCvC) has been strongly integrated into diverse research fields, and has enabled easy access to a variety of combinatorial libraries, 2-D macrocycles, and 3-D molecular cages that target many important applications, such as drug discovery, biotechnology, molecular separation, light harvesting, etc. DCvC relies on the reversible formation and breaking of rather strong covalent bonding within molecules. Therefore it combines the error-correction capability of supramolecular chemistry and the robustness of covalent bonding. Compared to those supramolecular interactions, dynamic covalent reactions usually have slower kinetics and require the assistance of catalysts to achieve rapid equilibrium. Although the scope of dynamic covalent reactions is rapidly expanding, the reversible reactions suitable for DCvC are still very limited. The identification and development of new dynamic reactions and catalysts would be critical for the further advancement of DCvC. This review covers the recent development of dynamic covalent reactions as well as their applications.