Metal azolate frameworks (MAFs) are an important subclass of MOFs, which have been actively investigated in more than 10 years. Compared with MOFs based on other organic ligands, the framework structures of MAFs are relatively more designable and have higher thermal and chemical stability and interesting properties in molecular adsorption, separation, sensing, catalysis, and so on. With a series of selected examples, the progress in chemistry of porous MAFs will be outlined and discussed in this chapter.