Abstract: An experiment is conducted to study the active earth pressure of cohesionless soil with limited width behind retaining wall in three different modes, which are translational motion, rotation around bottom and rotation around top. In the experiment, the failure modes of the soil and the distribution of the active earth pressure with different backfill widths are observed. The results show that the failure surface of the limited-width soil behind the retaining wall is a continuous one, which continuously moves to the outside and approaches a fixed position with the increase of the backfill width. But the failure surface of cohensionless soil is always located inside the Coulomb failure surface. Furthermore, the actual active earth pressure is less than that calculated by the Coulomb's theory, and the difference increases with the decrease of the backfill width, which indicates the Coulomb's theory is not applicable anymore for the backfilled soil with limited width. In addition, the motion patterns of retaining wall have great effects on the distribution of the active earth pressure. When the motion of retaining wall is translational, the earth pressure increases to a peak value first, then decreases with the increase of depth; when the retaining wall is rotating around the bottom, the earth pressure linearly increases with the increase of depth; and when it is rotating around the top, a significant earth arch effect is observed at the upper part of the retaining wall