Super small metal particles (<2nm, thereinafter referred as nanoclusters) represent an emerging new type of alternative fluorescent probes due to their excellent biocompatibility, tunable emission, large Stokes shift, and long fluorescence lifetime. However, the low quantum yield being the most serious weakness limits their practical applications. The goal of this project is to develop a hybridized hierarchical nanostructure which contains metal particles of 20_50nm (thereinafter referred as nanoparticles) and small metal nanoclusters to greatly enhance the fluorescence emission of the small metal nanoclusters by coupling surface plasmon resonance of the big metal nanoparticles. This project focuses on increasing the fluorescence quantum yield of metal nanoclusters for bioimaging applications by utilizing metal surface plasmon resonances through controlling the morphology and size of the big metal nanoparticles, as well as the distance between the nanoparticles and the nanoclusters. This study investigates the mechanism of fluorescence coupling with surface plasmon resonance, establishes a basic theoretical understanding for solving the low quantum yield issue of metal nanoclusters. The research outcomes will help to develop efficient targeting fluorescent nanoprobes for imaging and diagnosis of tumors for medical application.