Xanthan gum is a natural complex exopolysaccharide produced by the phytopathogen Xanthomonas campestris pv. campestris(Xcc). It is polymerized from a repeating unit, which consists of the D-glucosyl, D-mannosyl, and D-glucuronyl residues and variable proportions of O-acetyl and pyruvyl residues. Because of xanthan gum’s outstanding rheological properties, it is widely used as a stabilizer and thickener in many industries including food, pharmaceutical and cosmetic industries. This review summarizes its structural characteristics, rheological properties, applications and fermentation conditions, as well as its biosynthetic pathways and regulation networks, paving the way for its further study.