Silver tin oxide composite powders were synthesized by the hydrothermal method with a silver ammine solution and a Na2SnO3 solution as raw materials. H2C2O4 was used as the co-precipitator of silver ions and tin ions. The co-precipitation conditions were investigated. The results show that the co-precipitate of Ag2C2O4 and Sn(OH)4 is available when the pH value of the solution is 4.27-8.36. Using the obtained precipitate as precursor,the reduction of Ag+ and the crystallization of tin oxide were carried out simultaneously by the hydrothermal method and silver tin oxide composite powders were obtained. The composite powders were characterized by X-ray diffraction (XRD) analysis,scanning electron microscope (SEM),and energy spectrum analysis. The results show that the silver tin oxide composite powders are small with a diameter of about 2 μm and with homogeneous distribution of tin. The silver-tin oxide composite powders were synthesized by the hydrothermal method with a silver ammine solution and a Na2SnO3 solution as raw materials. H2C2O4 was used as the co-precipitator of silver ions and tin ions. The results show the that the co-precipitate of Ag2C2O4 and Sn (OH) 4 is available when the pH value of the solution is 4.27-8.36. Using the obtained precipitate as precursor, the reduction of Ag + and the crystallization of tin oxide were carried out simultaneously by the The composite powders were characterized by X-ray diffraction (XRD) analysis, scanning electron microscope (SEM), and energy spectrum analysis. The results show that the silver tin oxide composite powders are small with a diameter of about 2 μm and with a homogeneous distribution of tin.