Au nanoparticles (AuNPs) have attracted much attention due to their high chemical stability and excellent optical properties [1]. Localized surface plasmon resonance (LSPR) of AuNPs is applied as various sensors and solar cells [2]. Since LSPR depends on to the size, shape and concentration of the AuNPs, it is necessary to consider how to control these parameters of AuNPs. The aim of this study is to control the size and concentration of AuNPs formed by laser irradiation and thermal annealing in furnace. Au films with the thickness up to 2 nm were formed on borosilicate glass substrates by the vacuum evaporation method. The obtained samples were irradiated by the Nd:YAG laser in the range of intensities from 75 to 180 MW/cm2. While in case of thermal annealing, the temperature was T=400℃ and the time of curing was varied from 24 to 72 hours. As a result, AuNPs were formed on the surface of the substrates. The process of the nanoparticles formation by the laser radiation can be explained by two different mechanisms depending on the laser intensity. At the lowest laser intensity I=75 MW/cm2 (Fig.1.a), the rupture of Au film at the temperature close to the melting point due to surface tension takes place. As a result, Au nanoparticles are formed on the boundaries of the film. At the highest laser intensity I=180 MW/cm2 (Fig.1.b), when the temperature of the Au film is above the melting point the full conversion of the Au film into nanoparticles takes place. Due to the evaporation of small Au nanoparticles disappear, but bigger grows. The increase of laser intensity from 75 to 180 MW/cm2 leads to the increase of AuNPs diameter from 113 to 180 nm and decrease of their concentration, as shown in Figs.1,3. On the other hand, the thermal annealing at T=400℃ from 48 to 72 hours leads to the nanoisland formation with the non-spherical shape and their dividing into several islands according to the spinodal dewetting model [3]. As the result the mean diameter of AuNPs is decreased from 161 to 85 nm but concentration increases.