A series of Ag-based catalysts for the synthesis of indole by the reaction of aniline and ethylene glycol were prepared and characterized by XRD. The results indicated that the activity and stability of Ag/Si02 catalyst were increased after adding Zn, Mn, Cd, Mg and Ca promoters. The reason why they could increase the stability of the catalyst might be due to them possessed basic properties and excellent performance of dehydrogenation and dehydration. For the catalysts, there were two main causes of deactivation during the reaction:carbon deposition and silver sintering at 300-400°C. The activity and selectivity strongly depend on the loading amount and grain size of Ag. The catalysts with small grain size of Ag had higher activity than those with big grain size. Some catalysts showed high catalytic activity in this reaction.