A　high　yield　of　the　dimer-type　heterostructure　of　Ag/ZnO　nanocrystals　with　different　Ag　contents　is　successfully　prepared　through　a　simple　solvothermal　method　in　the　absence　of　surfactants.　The　samples　are　characterized　by　X-ray　diffraction,　transmission　electron　microscopy,　X-ray　photoelectron　spectroscopy,　UV-vis　spectroscopy,　and　IR　spectroscopy.　The　results　show　that　all　samples　are　composed　of　metallic　Ag　and　ZnO;　Ag　nanoparticles　locate　on　the　surface　of　ZnO　nanorods;　the　binding　energy　of　Ag　3d5/2　for　the　Ag/ZnO　sample　with　a　Ag　content　of　5.0　atom　%　shifts　remarkably　to　the　lower　binding　energy　compared　with　the　corresponding　value　of　pure　metallic　Ag　because　of　the　interaction　between　Ag　and　ZnO　nanocrystals;　the　concentration　of　oxygen　vacancy　for　the　assynthesized　samples　varies　with　the　increasing　Ag　content,　and　the　Ag/ZnO　sample　with　a　Ag　content　of　5.0　atom　%　has　the　largest　density　of　oxygen　vacancy.　In　addition,　the　relationship　between　their　structure　and　photocatalytic　property　is　investigated　in　detail.　It　is　found　that　the　photocatalytic　property　is　closely　related　to　its　structure,　such　as　heterostructure,　oxygen　defect,　and　crystallinity.　The　presence　of　metallic　Ag　nanoparticles　and　oxygen　vacancy　on　the　surface　of　ZnO　nanorods　promotes　the　separation　of　photogenerated　electron-hole　pairs　and　thus　enhances　the　photocatalytic　activity.　©　2007　American　Chemical　Society.