Series of AgxCo (x = 0 similar to 0.08) oxide catalysts prepared by coprecipitation (CP) was investigated in the N2O decomposition. The addition of Ag into cobalt oxide significantly enhanced the activity of the catalyst by both greatly decreasing the average size of the Co3O4 crystallites and significantly weakening the Co-O bond. Due to the function of Ag weakening the Co-O bond, the oxygen vacancies regeneration over the catalyst surface was significantly facilitated under the reaction conditions, which endows the Ag0.04Co(CP) catalyst a much lower activation energy compared with the cobalt oxide for the reaction. Moreover, the Ag0.04Co(CP) catalyst exhibited much stable activity under the presence of 5 vol% O-2, 2 vol% H2O and 100 ppmv NO, which is better than that of K doped cobalt oxide reported in literature.