【Objective】 Change in soil moisture of a collapsed wall is one of the main factors leading to occurrence and development of collapse therein. Rainfall can cause unstability and eventually collapse of the wall. During this process, the swell-shrink characteristics of the solum as affected by soil water content play an important role in mound collapsing. In the past, studies paid most attention to effect of water content on the swelling-shrinkage characteristics only in a single soil layer. 【Method】 With the collapsing mounds or walls typical of Anxi County of Fujian as object, effect of water content on the swell-shrink characteristics of a solum or a mound relative to soil layer was studied via indoor tests on no-loading expansion rate and linear shrinkage rate. 【Result】 Results show that no-loading expansion rate of the soil, regardless of layer, decreased with increasing initial water content, while linear shrinkage rate was in a reverse trend. Initial water content exhibited an obvious exponential decreasing relationship with soil unloading expansion rate in all soil layers and the relationship could be fitted with a regression equation of δ_e=ae^{(-ω /b)} +cwith R²＞0.96. But initial water content did have a significant exponential increasing relationship with linear shrinkage rate of the soil, regardless of soil layer, and the relationship could be fitted with a regression equation of δ_sl =ae^{(ω /b)} +c with R²＞0.96 in all soil layers. So initial water content had a good exponential relationship with no-loading expansion rate and linear shrinkage rate. In the same soil layer, the expansion varied more greatly than the shrinkage did in extent. Comparison between soil layers in extent of the variation of expansion and shrinkage rates shows that the red soil layer was 2.58% and 3.33% higher than the sandy soil layer, and 3.61% and 4.67% higher than the detritus soil layer, respectively. 【Conclusion】 These irreversible phenomena of swelling-shrinking might be the main cause to form cracks in the solum, which then eventually lead to soil collapse. This work is of certain important significance to understanding the causes and mechanism of collapsing of mounds.