Low energy electron diffraction (LEED), low temperature scanning tunneling microscopy (STM) and density functional theory (DFT) based calculations were used to determine the evolution of the silicene structure on a Ag(111) surface. The phase diagram of the structure was obtained using LEED patterns. The corresponding atomic arrangements were confirmed using STM observations. Results show that the structure of silicene is controlled by the substrate temperature during deposition. Finally, we succeeded in synthesizing silicene on silicene/Ag(111), i.e. bilayer silicene.