The effects of gold film thickness, refractive index of dielectric and its thickness on extraordinary transmission properties of gold aperture array-dielectric and gold-dielectric aperture array are studied using the finite-difference time-domain (FDTD) method. The results show that both structures have a good extraordinary transmission property, which suggests that surface plasmon polariton (SPP), formed by coupling of light and free electron charge density wave of gold film surface, plays a key role in enhanced transmission. The gold film thickness is the major factor affecting the extraordinary transmission property, and its decay length is 35 nm; the thickness of dielectric film adjacent to the gold film has minimal impact on the extraordinary transmission property. The refractive index of dielectric has a distinct impact on the extraordinary transmission property, and the refractive index of 1.8 may lead to a good extraordinary transmission property.