With the development of the aquaculture industry, the stocking density has increased and the outbreaks of bacterial diseases have become more and more frequent. Nowadays, antibiotics are still the main control tood against bacterial infection. However its massive and irregular use makes the problem of drug resistance more serious. In order to effectively prevent and control aquatic bacterial diseases, accelerate the sustainable development of the aquaculture industry, and promote industrial transformation, it is urgently needed to seek new antibacterial methods to alleviate the current situation. Bacteriophages (phages) are viruses that specifically infect bacteria. A bacteriophage, also known informally as a phage, is a virus that infects and replicates within bacteria and archaea. They have the advantages of strong specificity, less resistance, easy to be metabolized, easy development, and low cost. Phages have been widely studied worldwide, and also have been applied to the prevention and control of various diseases. The related products have also been well- recognized, but the limitations cannot be ignored. This article first comprehensively introduces the principles and advantages of phage therapy, and then reviews the research progress of phage therapy in bacterial diseases of aquaculture animals. Subsequently, the existing dilemmas of phage therapy and coping strategies were discussed. Finally, a prospect is made on this basis, hoping to provide references for the follow-up research on the application of bacteriophages in aquaculture.