Abstract: The occurrence of diseases in aquaculture animals is becoming more and more frequent, resulting in substantial economic losses for the entire industry. Oral vaccines offer an effective prevent disease prevention without causing a stress response, making them particularly well-suitable for safeguarding aquatic animal health. Bacillus, a common probiotic in aquaculture, is capable of forming spores with strong stress resistance, which can be used to construct a spore surface display system as an ideal platform for antigen presentation. Therefore, the use of spore surfaces to display oral vaccines and stably deliver antigens to the intestine has attracted more and more attention. We reviewed the spore, Bacillus competence, and the spore surface display system. In addition, this article focuses on the research and application of spores as oral vaccine vectors in the prevention of bacterial, viral, and parasitic diseases in aquatic animals. It aims to serve as a valuable reference for the development of efficient and stable oral vaccines for aquaculture animals.