Fruit flies （Diptera: Tephritidae）constitute a group of important agricultural pests, that harm crop plants and fruits, seriously affecting agricultural production and trade in fruit and vegetables. They are classified as important quarantine pests in many countries. Symbionts may provide proteins which are absent in the diets for fruit flies and help them keep normal ovipositional ability. They can also improve host adaptability to the environment. Twenty one genus of bacterial symbionts, including Enterobacter, Klebsiella, Citrobacter, Pseudomonas, Providencia, Erwinia, Acetobacter, Serratia, Proteus, Hafnia, Cedecea, Arthrobacter, Lactobacillus, Micrococcus, Streptococcus, Staphylococcus, Vibrio, Hafnia, Deinococcacea, Bacillus, Wolbachia, and one genus of fungi symbiont (Candida) have been identified so far. Klebsiella pneumoniae, Klebsiella oxytoca, Pantoea agglomerans, Citrobter freundii, Enterobacter cloacae and Wolbachia are the most prevalent symbionts and have always been paid close attention to. Wolbachia as primary symbiont often was found in the ovary and ovipositor of hosts, while other second symbionts reside in the hosts′ digestive tract. The association between symbionts and host fruit flies′ population, distribution, invasion ability and host plant have not been definited. Research on fruit fly symbionts has the potential to make a significant contribution to find new baits, enhance the adaptability of sterile male adults and develop new control methods against this group of pests. In this review, the distribution, species, biological characteristics, function of symbionts in fruit flies and related research methods are summarized.