Refrigerant is the blood of refrigeration systems. Since the synthetic refrigerants were developed, refrigeration technology has experienced a rapid development. However, this also brings environment problems, such as ozone depletion and global warming, which turns into the main challenges for traditional synthetic refrigerants. Based on the new version of the Montreal Protocol 2014 Assessment Report written by UNEP RTOC, the proceedings of the 25th International Congress of Refrigeration 2015 and the 11th IIR Gustav Lorentzen Conference on Natural Refrigerants 2014, a review of the latest research and development of refrigerants was presented in this work. Different aspects were discussed including current situation of refrigerants in different types of refrigeration units, properties of novel low-carbon refrigerants, latest development of international standard for flammable refrigerants, issues that need concerning in the application of novel low-carbon refrigerants and the possible trends for alternative refrigerants.