Vapor-liquid equilibrium (VLE) data of lubricating oil + refrigerant mixtures are necessary for the design and simulation of the refrigeration system. In this paper, the saturated vapor pressure data and VLE data of different mass fractions of the mixture (ethyl fluoride (HFC-161) + polyol ester oil (POE)) in the temperature range from (253 to 333) K were measured by a single-phase cycle method. Throughout the observation of the overall experiment, there was no stratification and no sediment generation, and the color of liquid had no change in the equilibrium cell before and after the experiment. The above-mentioned content suggested that the different ratios of HFC-161 and lubricating oil POE could be miscible. Meanwhile, the saturated vapor-pressure data of the mixture (HFC-161 + POE) revealed that POE had a very small effect on the saturated vapor pressure of the mixture (almost negligible) when the mass fraction of lubricating oil was less than 0.1 of the mixture; POE had a bigger effect on the saturated vapor pressure of the mixture when there was more oil in the mixture. In addition, using the nonrandom two-liquid (NRTL) model and the Wilson model, VLE experimental data were correlated, and the results showed that they had a good agreement with correlated results, to the average and maximum of relative pressure deviations. The results derived from the NRTL model were better than those derived from the Wilson model.