We present a novel multifunctional magnetic Ag nanoshell with sandwichlike nanostructure, which is composed of a yolk-egg-like magnetic silica core and a continuous Ag nanoshell coating. First, yolk-egg-like magnetic silica was prepared by a facile one-step sol-gel method to embed the magnetic narroparticles at the boundary between inner silica spherical core and outer silica shell. Then Ag nanoshells were coated by electroless plating method, forming a multiplayer sandwichlike nanostructure. The plasmon resonance peaks can shift across a wide wavelength range by tuning the Ag shell coverage and thickness. The magnetic Ag nanoshells fuse the broad NIR absorption property and superparamagnetic property into one particle, possessing promising biomedical applications such as magnetic-field targeted photothermal therapy agents and multimodal molecular probes.