Ag/CeO_2MnO_2 catalysts were prepared by incipient wetness impregnation method and used for Acrylonitrile oxidation reaction. The activity of Ag/CeO_2MnO_2 catalyst was compared with the reaction parameters, such as catalyst loading, oxygen concentration, space velocity and reaction temperature. The catalytic activity is found to be higher over the condition of high catalyst loading, high oxygen concentration and low flow rate. NOx is one of the byproducts and can be well control in low temperature.