According to the general boundary conditions of the electromagnetic field, the reflection and transmission laws of electromagnetic waves on the charged interface of two different media are studied. It is proved that the reflection and the refraction laws for the charged interface are the same as that for the uncharged interface. The amplitude reflection coefficient and the amplitude transmission coefficient are derived for the reflection and transmission of the parallel and vertical components of the incident waves on the charged surface, i.e. modified Fresnel formulas. Due to the different interface conduction characteristics, surface charge distribution on the interface of two different media will affect the surface conductivity of the interface, and the modified Fresnel formulas are related to the surface conductivity and electromagnetic impedance of free space. The calculation results show that the amplitude reflection coefficient and the amplitude transmission coefficient as well as the reflectance and the transmittance will change when the surface conductivity varies with the surface charge density or the interface characteristics.