Glycodrug is an important chemical medicine category derived from biological carbohydrates and their mimics. However, the fundamental logic and features of glycodrugs are obscure issues. To make it easier to understand, four key characters of glycodrugs are extracted for reference. First, Glc relating drugs are key guards in glycometabolism. Second, Rib, GlcN/GalN, and Sia relating drugs are efficient modulators in life signaling regulations. Third, rare sugar relating drugs are effective weapons against various pathogens. Finally, glycosylation modifications are helpful strategies for druggability enhancement. In light of such key characters, more innovative glycodrugs will emerge in the future.