It has been found that CFCs can lead to ozone depletion and global warming when they are released into the air. In order to protect the ozone layer, the use of the traditional refrigerant has been forbidden gradually, and the research on the substitution of new refrigerants is carried out urgently in the world. In this paper,the substitution principle is introduced,and the research situation of new refrigerants at home and abroad is also described. The application of ammonia refrigerant is discussed in detail,and the developing direction of refrigerant also discussed.