In this paper, thermal-induced behaviors of a gold nanoparticle monolayer onglass slides are investigated. First, through horizontal lifting, gold nanoparticlemonolayers are transferred from a water/hexane interface to glass slides. Thenthermal treatment is carried out in air, after which an apparent color changeof the obtained samples is noticed, depending on the annealing temperature,reflecting a shift of the surface plasmon band (SPB). Depending on the trend ofSPB shift, the overall thermal process is divided into three stages. In the firststage, SPB shows a redshift trend with concomitant band broadening. Furtherincrease of the annealing temperature in the second stage results in an increase ofinterparticle distance. Thus an apparent decrease in absorbance takes place withSPB shift to shorter wavelengths. In the third stage, the SPB redshifts again.Bulk refractive index sensitivity (RIS) measurements are taken by immersing theobtained samples in solutions of various refractive indices and a linear dependence ofRISλ andRISext on refractive index is concluded. In particular, the influences of parameters such as particlesizes, location of SPB, substrate effect and morphology effect on RIS are discussed indetail. The corresponding performance of each sample as a localized surface plasmonresonance-based sensor is evaluated by a figure of merit (FOM) represented asFOMλ andFOMext. It is found that the optimum annealing temperature is500 °C. In terms of nanoparticle sizes, samples with a 35 nm gold nanoparticle monolayer performbetter than those with 15 nm. The current strategy is simple and facile to achieve finecontrol of the SPB, in which large-size precision instruments or complex chemosynthesis areunnecessary. Therefore, this method has not only significance for theory but also usefulnessin practical applications.