The adsorption behaviors of the C2H4 molecule on the surface of the 7-atom Ag-Cu clusters are systematically investigated based on generalized gradient approximate density functional theory. The top site adsorption of C2H4 on the Ag7 cluster is physical adsorption, and the top site adsorption on the other clusters is chemical adsorption. The bridge site adsorption of C2H4 on Ag7 and Cu7 clusters is physical adsorption, while the chemical adsorption of C2H4 on the other clusters undergoes the transformation from the bridge site to the top site adsorption on the Cu atoms. In particular, the original structures of Ag5Cu2 and Ag4Cu3 clusters deformed significantly when C2H4 was adsorbed on their bridge sites. The adsorption of C2H4 on the bridge site of the Ag5Cu2 cluster is more stable than that on the top site, and the adsorption of C2H4 on the top site of the remainder clusters is more stable than that on the bridge site. Overall, the Ag2Cu5 cluster is the most stable for C2H4 adsorption configuration among all the studied clusters.