Mixed refrigerant and preparation method thereof

The invention discloses a mixed refrigerant and a preparation method of the mixed refrigerant, and the mixed refrigerant comprises the following components in percentage by mass: 40-60% of pentafluoroethane, 10-30% of a solvent, 1-5% of a catalyst and the balance of a solvent. 10 to 35 percent of difluoromethane; 5 to 25% of difluoroethane; and 5-20% of 1, 1, 1, 2, 3, 3, 3-tetrafluoropropene. The mixed refrigerant provided by the invention has a relatively low GWP value which is reduced by 40-60% compared with a refrigerant R404A, and the mixed refrigerant provided by the invention has similar physical properties (for example, the physical properties are relatively close to those of the refrigerant R404A) compared with an existing refrigerant, so that in the replacement process, lubricating oil does not need to be replaced, a refrigerating system does not need to be greatly modified, and the cost is reduced. In addition, the mixed refrigerant provided by the invention has the advantages of low toxicity, easil