Plant crystals are one of the metabolin that have peculiar morphological structure and physiological function. They are widespreading and have been found in more than 500 floristics. Crystals have multiple shapes, such as raphid, column crystal, prism, sand crystal and cluster crystal and have multifarious types, including crystals of calcium oxalate, cystolith, silicon plastid, calcium sulfate crystal etc. They also have significant functions, for instance, calcium regulating, plant defense and protection, detoxifing heavy metal, ionic equilibrium, increasing stress tolerance and others biological functions. The synthesis of crystal is associated with calcium ion absorbed in vitro and transported in vivo, the biosynthesis of oxalate, and the coupling process of calcium ion and oxalate. The growth and development of crystal has close relationship with interaction among vacuole, idioblast regulation, and others eucaryotic cell structures. Previous studies have been summarized in this paper in order to identify the areas of further research.