The multiple-scattering cluster method (MSC) has been used to study theoretically the sulphur K-edge NEXAFS of SO2 adsorbed on the Ag (110) at 1/2 coverage.It is shown that SO2 is adsorbed on the Ag (110) with S atom sitting in the hollow site and two O atoms being in an asymmetric geometry,the molecular plane is rotated from the (110) by approximately 52° and tited slightly towards the substrate.Compared to the case of the gas phase SO2,the O—S intramolecular bond length is elngated by (0.014±0.006)nm and the OSO bond angle is reduced by 15°±5° after adsorption.The resonance located between π* and σ* is proved to be induced by the interaction between SO2 and substrate.