The application status of main marine refrigeration units and the refrigerant has been analyzed in order to promote the process of the ship greenhouse gas emission reduction. It summarizes the usage and restrictions of the marine refrigerants by the environmental labels of the classification societies, the development of the marine refrigerants and the marine low global warming potential (GWP) refrigerant with application potential. The results show that the main marine refrigeration system currently uses the steam compression refrigeration, and the commonly used refrigerants are R134a, R404A, R410A, R407C and R407F. The environmental labels of CCS, DNV GL, ABS, BV and LR require the Ozone depletion potential (ODP) of the marine refrigerants to be zero, and the environmental labels with the higher level require the GWP of the marine refrigerants less than 2 000. Special consideration of flammability and toxicity are required for the refrigerants with flammability and toxicity. The marine low GWP refrigerants mainly include the hydrous ferric oxide (HFO) refrigerant R1234yf, the HFO mixed refrigerant series of R449A, R513A and R454, and the natural refrigerants of NH ₃ and CO ₂. The results can be used as references for the design and study of the marine refrigeration system.