Abstract: Aseries of Solid uranyl formates ere prepared and their infrared absorption spectra were investigated. It was found that the anti-symmetric vibration frequencies of uranyl group,vα,for these compounds were in the range of 912-952 cm^-1,and the vα absorption peaks were single-shaped for some uranyl formate double salts. According to above vαabsorption spectra,the decomposition of basic uranyl formate was also investigated by using TEA-CO₂laser. The experimental results showed that the photodecomposition reaction could take place only under intense irradiation at the frequency resonant with the vα of uranyl group.