Abstract: By using the eigenvalue equation and finite-difference time-domain (FDTD) algorithm, the sensing characteristics of surface plasmon resonance based on the rhombic gold nanoparticles array, embedded in the silica substrate, have been studied. An analytical expression for the variation of resonance mode with the embedding depth is derived. Its predicted results are consistent with the numerical simulations, which prove the reasonability and validity of the physical model, in which the asymmetry of the upper and lower dielectrics in the surface of gold nanoparticles array can be equivalent to monolayer dielectric grating. The physical mechanism and influence factors of the phenomenon that multi resonance peaks occur in the transmission spectrum are explained theoretically, and the reasons that transmission spectrum is sensitive to the embedding depth, axial ratio and array period, are also discussed. In addition, the sensing performance of the array structure is analyzed further, which could provide the way to design multi-band substrate for SPR sensor.