Microwave heating of Ag ⁺ in polyvinyl alcohol (PVA) is an effective method to synthesize silver nanoparticles (AgNPs), a broad-range antibacterial agent. However, the microwave may cause PVA solution to dry out and degrade. This study is aimed at investigating the effect of microwave irradiation on different concentrations of PVA in PVA/Ag ⁺ solution in short periods of exposure. Fourier-transform infrared (FTIR) spectroscopy was employed to evaluate chemical changes of samples with different exposure times and PVA concentration. The results confirm the redox reaction of Ag ⁺ with PVA. In addition, Ag ⁺ reduces the rate of hydrolysis of PVA, and the ether bridges are limited by the spatial structure.