Abstract: The relations of the mass fraction and temperature of mixtures of water and dimethyl sulphoxide (DMSO) to refractive index are theoretically and experimentally studied. The empirical formula fit for calculating the refractive index of the mixture is chosen by comparing the simulation results of several classical models. Then the effects of mass fraction and temperature of the mixture of aqueous gold colloids and DMSO on localized surface plasmon resonance are studied. The theoretical and experimental results show that the mass fraction of the mixture of aqueous gold colloids and DSMO has linear relationship with the resonance wavelength of localized surface plasmon in a large range. The resonance wavelength of the mixed gold colloids increases by 1367 pm when the temperature increases from 20 ℃ to 60 ℃, and its temperature sensitivity is 34 pm/K. The increase of resonance wavelength with mass fraction is 8.5103 pm in a 0-100% mass fraction range.