Ionic covalent organic frameworks (iCOFs) are an emerging subclass of COFs which contain either charged skeleton or charged pore interface. Besides the intrinsic advantages of neutral COFs such as large specific surface area, structural tunability and designability, the ionic moieties of iCOFs act as interaction sites to bind with the oppositely charged guests, thus endows iCOFs with functionality such as selective adsorption and ions conduction. The ionic repulsion between layers caused an easier exfoliation of iCOFs into ionic covalent organic nanosheets (iCON). These promising features have attracted considerable interests. In recent years, the building blocks, reaction types, topology structures and synthetic strategies of iCOFs have been studied extensively, paving the way of various applications such as molecular adsorption/separation, catalysis, energy conversion, proton conduction and biomedical engineering. In this review, we summarize the research progress of iCOFs based on design, synthesis and applications. The current challenge and future directions for the research of iCOFs are discussed as well.