Waste heat can be well utilized in absorption refrigeration systems. The auto-cascade absorption refrigeration system couldreach a lower temperature than traditional one because the non-azeotropic mixed refrigerants were used. In this paper, performances of an auto-cascade absorption refrigeration with R23/R134a/DMF (Dimethylformamide) as the working substance was analysed. Theoretical analysing results showed that, to some extent, the COP couldbe increased when the low pressure of the system decreased or the high pressure increased. The reasonable high pressure was the high turning point pressure, and reasonable low pressure was the low turning point pressure. The COP of the system monotonously increased with the increase of the mole fraction of R23. The lowest R23 mole fraction one should be the most promising
