Compacted clay is extensively used as foundation materials, generally presenting unsaturated state. Understanding the soil arching effect in unsaturated compacted clay under unloading is meaningful for ensuring its performance, but nowadays still limited. A series of two-dimensional trapdoor model tests were conducted to investigate the stress redistribution and deformation mechanism caused by the soil arching effect in unsaturated compacted clay under unloading. Different initial placement conditions (dry densities and water contents) of clay were considered. From the results of the trapdoor tests, the effect of the initial placement condition of the soil is significant for the characteristics of the soil arching effect in unsaturated compacted clay, including the deformation development and the stress redistribution. The results can provide a technical reference for estimating and fully using the soil arching effect in unsaturated compacted clay during geotechnical design.