In this paper,we focus on the fluorescence enhancement effect of photosensitizer cholorin f-ehter(CPD4) which was adsorbed on the surface with varied silver nanoparticles coverages.Substrates with varied coverages of silver nanoparticles(NPs) were prepared through the self-assembly method.The measurements of fluorescence images and the spectra of adsorbed fluorophores on silver NPs substrate were performed by the laser scanning confocal microscopy.The results show that the excitation rate and the total decay rate of admolecule are independent of the nanoparticles coverage when the coverage is lower(<30%),and they dramatically increase when the coverage approaches 40%,which demonstrates that the interparticle electromagnetic coupling is strong enough to enhance both the excitation rate and radiation rate.The experimental results and theoretical analysis both indicate that the strong interparticle electromagnetic coupling induced by dense arrangement of nanoparticles leads to stronger fluorescence compared with individual silver nanoparticles.