Marine communication technology is crucial in scientific research, national security, environmental monitoring and other fields, but facing challenges such as open channel and dynamic topology, secure transmission technology is particularly critical. Quantum communication technology, especially quantum key distribution (QKD), provides secure, interference-resistant, and efficient data transmission capabilities in the marine environment through the principles of quantum mechanics. This paper reviews the existing research results in the field of marine quantum communication and explores the application of quantum communication in the ocean, including the evaluation of the performance of QKD under different water quality conditions and the experimental study of quantum cryptography in free-space seawater. The study shows that quantum communication technology can effectively cope with the complexity of the marine environment and has important application prospects in future marine communications.