The paper presents a theoretical study on the comparison of new refrigerants R1234yf, R32 and conventional refrigerant R134a for household refrigerators and commercial refrigerating machines. The theoretical reference cycle used for the comparisons is the superheated and subcooled refrigeration cycle with condensation temperature of 50°C and evaporation temperatures of -30, -25, -20, -15 and -10°C. The parameters to be calculated for the comparisons are suction pressure, condensing pressure, discharged temperature, specific volume cooling capacity, coefficient of performance COP and exergy efficiency of the cycle. The results showed that the calculated values of R1234Yr and R134a are nearly equal. Meanwhile R32's suction pressure, condensing pressure and especially discharged temperature are too high, coefficient of performance and exergy efficiency are from 12 to 13 percent lower than those of R1234yf and R134a.