Abstract: The Argic horizon is a primary diagnostic criterion of Luvisols. In general, the argic horizon is formed due to long-term leaching under humid condition. While the argillic process could be interrupted by climate change and soil erosion. The purpose of this paper was to study the effect of soil erosion on the identification of Argic horizon and classification of Alfisols group. The basic characteristics and physical and chemical properties were analyzed in the sixteen Alfisol profiles with thirty-one argillic horizons in Shanxi Province on the Loess Plateau. The results were showed as following: (1) There was obvious transition of morphological characteristics between Argic horizon (Bt) and its over layers in 16 soil profiles due to illuviation process according to clay film, clay content, slit/clay ratio and the status of lime reaction. (2) About 16 leached soil profiles were classified into several soil subgroups such as Trunic Ferric-Ustic Luvisol, Petro Calcic-Ustic Luvisol, Typic Hapli-Ustic Luvisol, and Calcic Hapli-Ustic Luvisol according to their diagnostic layers and features. (3) The Trunic subgroup had obviously lower clay content than the other subgroups, while it was opposite to the slit/clay ratio. (4) The soil profiles were classified into Alfisols according to argic horizon identified from existence of clay flim, because the paleo-argic horizons were denuded to earth surface. The Chinese Soil Taxonomy classified diagnostic horizons of soil profile according to its material composition near 1.5 m or less than 2 m. The paleo-argic horizons were identified as clay parent material taken as family classification criterion in Soil Genetic Classification system.