In this paper, a single-source equivalence principle algorithm (SS-EPA) is applied to solve composite scattering from multiple objects above a rough surface. In the scattering problem of objects above a rough surface, the number of unknowns on equivalence surfaces is much less than that on the rough surface and objects using principle algorithm (EPA). The SS-EPA is based on the extinction theorem, which indicated the electric currents can be expressed by magnetic currents on the equivalence surface and vice versa. In the process of couplings between objects (or surface) and the equivalence surfaces, and couplings between the equivalence surfaces, only electric (or magnetic) currents are needed to calculate. Thus, SS-EPA is more efficient and numerical results show good agreements with those of the traditional EPA.