Abstract: α-galactosidase (α-gal, EC 3.2.1.22) is a kind of exoglycosidase that can specifically catalyze the hydrolysis ofα-galactoside bonds. It has the ability to hydrolyze theα-1, 6-galactoside bonds involved in galacto-oligosaccharides such as melibiose, raffinose, and stachyose, galactomannans, galactolipids and glycoproteins. It has widely been found in animals, plants and microorganisms (archaea, bacteria, fungi) and etc. As its catalytic specificity, α-Gal has been widely used in such fields as food, feed, agriculture, medicine and light industry, and it is considered as one of the most promising enzyme preparations.α-Gal from different species and families exhibit great differences in sequence homology, advanced catalytic structure, catalytic active site, enzyme-substrate binding mechanism, and thermal stability etc., which greatly limits the development and application ofα-Gal. Compared with studies onα-Gal in microorganisms, studies onα-Gal in plants are still relatively limited. In plants, α-Gal is widely involved in important physiological processes such as leaf development and senescence, seed development and germination, fruit softening and ripening and stress response. However, the physiological and molecular mechanisms ofα-Gal involved in these processes mentioned above have still been unclear. Therefore, based on the previous researches and reports onα-Gal, the origin, distribution, classification, catalytic property and applications, GH protein family evolution ofα-Gal and its biological functions on the biosynthesis, transport, unloading and catabolism of RFO, seed development, dehydration tolerance and germination, response to high and/or low temperature, salt and other abiotic stresses, and cell wall remodeling in plants are mainly reviewed in this paper.