The formation of an albic horizon in stagnic anthrosol has a special significance to genesis and development of the soil. To explore causes of the formation, four profiles of stagnic anthrosols with an albic horizon (E-A1, E-A2, E-A3 and E-A4) and and one (Ref), the same in parent material but without the horizon, as reference, in the Taihu Lake region were sampled for analysis of morphological characteristics, soil mechanical composition , clay mineral composition, contents of iron oxides, and geochemical characteristics of macro- and trace-elements. Of the five soil profiles, soil particle size compositions were dominated with silt, which accounted for 60%~75% and did not vary much between soil layers in the profile, with variation coefficient being < 10%. Contents of macro and trace elements did not vary much either, with CVs being less than 10%. All these indicated albic horizons developed from parent materials similar to those the overlying and the underlying layers did from. However, in Profile E-A1, the albic horizon was quite high in silt content (75.04%) and in CV of medium-fine silt (38.05%) and medium-fine silt/coarse silt (61.85%) as well, which indicates that the profile is not uniform in parent material. All these demonstrate that the variations of soil properties in Profiles E-A2, E-A3, E-A4 and Ref were caused by soil formation, while that in Profile E-A1 was also affected by the environment of sedimentation, besides soil formation. The albic horizons in Profiles E-A2, E-A3 and E-A4 are higher than their overlying and the underlying horizons in contents of smectite, illite, silt, coarse silt, SiO₂, CaO and Zr, but lower in contents of hydromica, chlorite, free iron, Al₂O₃, Rb, Li, Ba and REE. Profile Ref was quite similar to Profile E-A2, E-A3, E-A4 in all characteristics except that the albic process appeared only in the plow layer, which is not fit to be defined as albic horizon. In Profile E-A1, some soil properties were not spatially homogeneous, for instance, silt content is not the highest in the albic horizon, but increased with depth in the soil profile, which suggests that the formation of an albic horizon in stagnic anthrosols in the Taihu Lake region is a result of the subjection of loessial lagoon sediments to periodical alternation of flooding and draining mechanical washing and leaching of active iron during anthrostagnic process (Profiles E-A2, E-A3 and E-A4), or a result of the subjection of parent material to mechanical washing caused by rise and fall of the water surface in the lake during its sedimentation process and then to leaching of active iron during repeated anthrostagnic processes (Profile E-A1).