It is well-known that the promoter can enhance the selectivity to ethylene oxide (EO) of Ag catalyzed ethylene epoxidation. However, the selectivity enhancement on different crystal planes of Ag catalysts derived from various promoters is still indistinct. In this work, in order to get an atomistic insight into the synergistic effect between crystal planes and promoters on catalytic performance of Ag catalysts, we study ethylene epoxidation on Ag (1 1 1), (1 1 0) and (1 00) surfaces with the promoters of Re, Cs and Cu by density functional theory calculations. It is found that selectivity enhancement introduced by the promoters on Ag (1 1 1) surfaces is more obvious compared with that on Ag (1 1 0) and (1 0 0) surfaces. The sequence of EO selectivity on Ag (1 1 0) surfaces is Re < no promoter < Cs < Cu while it is Re < no promoter < Cu < Cs on Ag (1 1 1) and (1 0 0) surface. The adsorption strength of oxametallacycle intermediate works as a selectivity descriptor and has a negative correlation with valence electron depletion of surface Ag atoms. Therefore, the promoters can cause charge redistribution of Ag crystal surfaces and lead to the corresponding effect on the selectivity toward EO. In addition, the synergistic effect between promoter and crystal surface would affect the eletrophilicity of the surface atomic oxygen. We believe that this works would provide guidance to enhance the EO selectivity of Ag catalyzed ethylene epoxidation by rationally choosing suitable promoter for specific Ag crystal surfaces.