Low temperature critically affects the growth, reproduction and disease resistance of warm-water and tropical fishes. Because of climate changes, the effect of low temperatures on fish physiological processes is becoming increasingly pronounced. The molecular mechanism of cold tolerance in fish is a research direction highly relevant to basic life sciences and industrial applications. In this article, the current researches on the molecular mechanism of fish cold tolerance are reviewed from three aspects： physiological and biochemical basis, molecular pathway of responses to signal from low temperature and genetic mapping of cold tolerance traits. When in cold environment, fish will change the composition of fatty acids and enhance the activity of antioxidant enzymes to protect cells from damage, thereby coping with the stress of low temperatures. Meanwhile, the molecular mechanism of fish response to low temperature involves several signal pathways, and the activation and inhibition of these pathways are closely related to the cold tolerance of fish. The molecular mechanisms of cold tolerance in fish has important applications in aquaculture breeding. With advances in genomics technologies, the molecular basis of cold tolerance has been gradually revealed. Gene marker-assisted selection（MAS） and genomic analyses provide essential tools for screening genes related to cold tolerance, facilitating the breeding of cold-resistant fish species. These studies will not only help us understand how fish adapt to environmental changes, but will also open up new ways for the aquaculture industry to address climate changes and improve farming efficiency.