The improvement of the efficiency of spontaneous emission will give great help to the research and manufacture of optoelectronic devices such as single photon resource. The local density of elestromagnetic states was calculated which is represented by the electric dyadic Green′s function through the finite-difference frequency-domain method, the local density of states and the spontaneous emission rate in different metal materials, structures and wavelengths were analyzed, and the intrinsic physical mechanism was explored. The results show that the spontaneous emission rate of atoms can be greatly enhanced when surface plasmon polariton couple to the emiter, and different structure and the refractive indices of materials have different improvement of spontaneous emission rate. This research can provide important reference for the manufacture and optimization of optoelectronic devices.