In this paper, AgGaS 2 nanofilms have been prepared by a two-step process involving the successive ionic layer absorption and reaction (SILAR) and annealing method. Using AgNO 3 , GaCl 3 and Na 2 S 2 O 3 as reaction sources, the mixture films were firstly deposited on quartz glass substrates at room temperature, and then annealed in Ar environment at 200-500 ยฐC for 4 h, respectively. The effects of annealing temperature on structural and optical properties were investigated by XRD, UV-Vis, EDS and photoluminescence (PL) spectra. It was revealed in XRD results that ฮฑ-Ag 9 GaS 6 was contained in the samples annealed at 200 ยฐC, and this phase was decreased with increase of the annealing temperatures. When the sample was annealed at above 400 ยฐC, the chalcopyrite AgGaS 2 nanofilm was obtained. The preferred orientation was exhibited along the (112) plane. It was shown in atomic force microscopy (AFM) results that the grain sizes in AgGaS 2 nanofilms were 18-24 nm and the thin films were smooth and strongly adherent to the substrates. When the annealing temperature was higher than 400 ยฐC, it is an optimum condition to improve the structural and optical properties of the AgGaS 2 thin films. The room temperature PL spectra of AgGaS 2 nanofilms showed prominent band edge emission at 2.72 eV. Based on all results mentioned above, it can be concluded that the SILAR-annealing method is preferable to preparing high-quality AgGaS 2 nanofilms.