Soil behind retaining walls usually behaves with anisotropic strength, while it is taken as an isotropic material in the current earth pressure calculations. In order to study the effect of strength anisotropy on active earth pressure, a centrifuge testing method together with the measuring technology was proposed in this paper. Soils with anisotropic strength were modeled with two-dimensional granular materials deposited by metal bars with elliptical cross section. Two centrifuge modeling tests were carried out on the same material with different deposition angles. It was shown that the distribution of active earth pressure was affected by deposition angle. The action point of active earth pressure moved gradually to the bottom of the wall when deposition angle increases. The maximum active earth pressure with vertical deposition surface could be 40 percent larger than that with horizontal deposition surface.