To exploring the deformation character of the composite foundation with and without lateral constraint rammed soil-cement piles under cyclic loading, large-scale indoor model comparative tests are performed. Based on the test results, influence of the lateral constraint on the deformation of the composite foundation is analyzed. It shows that the settlement of the composite foundation with lateral constraint rammed soil-cement piles is smaller than that without the lateral constraint. Effect of the lateral constraint to reduce settlement of composite foundation becomes more significant with the increase of cyclic load ratio. Therefore, the lateral constraint has good effect to restrict the lateral deformation of soft soil and reduce the settlement of composite foundation.