To explore the nonlinear absorption (NLA) properties of the SnO₂ composite system, SnO₂ / Ag / SnO₂ (SAS) composited films were prepared by magnetron sputtering at room temperature. The NLA properties were investigated using femtosecond Z-scan technology at a wavelength of 800 nm. The results show that as the sputtering power of the Ag layer increases, the NLA type of the composite films changes from reverse saturated absorption to saturated absorption. According to the research results, adding the Ag layer can regulate the NLA type of composite films. In addition, by increasing the sputtering power of the Ag layer and the incident laser energy intensity, the NLA behavior of the composite films is improved. Compared with the monolayer SnO₂ film, the NLA coefficient (β) of the composite film has increased by 17 times. We provide a new perspective for the application of SAS composite films in optoelectronic devices.