In this work, Ag(NH3)2NO3 microcubes are obtained by directly evaporating the silver ammonia complex solution. In Na3Cit solution, each Ag(NH3)2NO3 microcube can crumble into lots of Ag3Cit sub-microcubes with uniform size, which serve as sacrificial templates to yield Ag sub-microcages. The as-obtained Ag cages possess ultra-high surface-enhanced Raman scattering (SERS) sensitivity towards R6G and thiram.