There is current interest in developing working fluids with low global warming potential (GWP). One such fluid is 2,3,3,3 - tetrafluoroprop-1-ene (R1234 yf). Although the thermophysical properties are critical for the selection of the potential refrigerant,only a few studies have been conducted on the thermophysical properties of refrigerant mixtures containing R1234 yf. In this work,we focused on the viscosity of R32 and the binary mixture of R32 /R1234 yf. The liquid viscosity of R32 and binary mixture of R32 /R1234 yf were presented over the temperature ranges of (263 to 350) K and (263 to 360) K at pressures up to 30 MPa using the vibrating wire viscometer. The measurements of mixtures containing the mole fraction (0.244 8,0.410 8,0.608 6 and 0.835 6) of R32 were carried out. The overall uncertainties of these results were 2.0 %. The experimental results of the pure R32 and the mixture were correlated with hard-sphere scheme. The average absolute deviations between the experimental results and the correlations were 0.28 % for R32 and 0.69 % for R32 /R1234 yf,and the maximum absolute deviations were 0.92 % and 2.09 %,respectively. Comparisons between measurements of this work and literatures were also presented.