Based on equilibrium analysis of forces and moment with inclined soil element, an analytical solution of earth pressure with inclined surface of fill and rough retaining wall was proposed, and the influence of slope angle of fill on earth pressure also was discussed. It is shown that the classical Rankine's earth pressure theory is a special case of the analytical solution with horizontal surface of fill and a smooth retaining wall. The results also show that the limiting rupture angle of a slidingwedge behind a retaining wall decreased with increasing slope angle of fill or friction angle between soil and a retaining wall, with the settled value of the internal friction angle of fill. The nonlinear character of earth pressure exhibited distinctly for the earth pressure along a retaining wall was obtained by an analytical solution. The value of earth pressure is 0 at the toe of retaining wall, consistent with the testing results. In addition, the value of earth pressure at the toe of the retaining wall will increase rapidly with increasing slope angle of fill. The analytical solution of earth pressure behind a retaining wall with fill of clay soils can be further studied with the investigative method we developed.