In this paper, a H-shaped metal hole array structure was proposed, then it was used to form the Fabry-Perot cavity to enhance the surface plasmon polarizations (SPP) coupling effect, hoping to obtain a better optical transmission phenomenon. H-shaped hole array consists of a vertical rectangular hole and two horizontal symmetrical rectangular holes, thus the effects of parameters of the holes, such as the length and the width, on the transmission characteristics were studied in detail by using the finite-difference time-domain (FDTD) method. Meanwhile, the refractive index sensing property was investigated based on the phenomenon. It is found that when the length and the width of the vertical rectangle holes are 300 and 120nm, and the length of the two symmetric rectangular holes in the horizontal direction are 60 and 10nm respectively, a strong transmission phenomenon can be realized. And the sensitivity of the refractive index can reach 389RIU/nm.