A three-dimensional molecular dynamics method with Finnis-Sinclair embedded atom potentials is used to study relaxtion of fcc Ag nanorods with crystallographic orientation[111] .Homeostasis of Ag nanorod relaxation is shown.Stable structures and potential energies and structure evolution of Ag nanorod are studied. A critical temperature of destabilization(T_c) is found.As temperature of the nanorod is less than T_c,the system keeps intact line form of crystal.As temperature is higher than T_c and less than melting point,the system collapses,fuses and then recrystallizes.As temperature is near melting point,a stable polyhedron bounded by(111) and(100) facets forms. As cross-section of Ag nanorod increases T_c and melting point decrease.As cross-section dimension is larger than 2 nm,T_c is close to the melting point.Destabilization exists in a narrow temperature range.