The work presents density (rho) and viscosity (eta) data of binary system polyethylene glycol 600 (PEG)+ dimethyl sulfoxide (DMSO) over the entire concentration range at T=(298.15, 303.15, 308.15, 313.15 and 318.15) K and atmospheric pressure. On the basis of density and viscosity values, the excess properties of PEG (1) + DMSO (2) mixtures, including excess molar volume (V-m(E)), viscosity deviation (Delta eta),excess free energies of activation (Delta G*(E)), and isobaric thermal expansion coefficient (alpha(p)), were calculated. At the same time, in order to conjecture the density viscosity under different conditions, the density and viscosity datawere fitted with the corresponding formula. The calculated results of V-m(E), Delta eta and Delta G*(E) were fitted with the Redlich-Kister equation to derive coefficients and estimate the standard deviations (sigma) between the experimental and calculated values. Moreover, the intermolecular interaction of PEG with DMSO was discussed on the basis of FTIR and UV-Vis spectral results of PEG (1) + DMSO (2) mixtures. The results indicated that there were the hydrogen bonding and interactions of hydroxyl hydrogen atoms in PEG with oxygen atoms in DMSO. (C) 2017 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.