Abstract: Taking the loess profile in the source region of Hanjiang River (Lijiahe village) and the Jialing River (Yangjiashan village) as the research object, explorated the weathering intensity of loess and its main attribution in soil taxonomy scientifically. The physical and chemical properties, grain size, element composition, aggregates of soil profile and so on were analyzed and compared. The results of experiment show that the soil weathering characteristics in this two river source regions are obviously different: (1)The soil aggregates in this two regions are mainly distributed in the range of 0.25~1 mm, but the contents of big aggregates (R_0.25 is 83.73%), the values of mean weight diamet (MWD is 2.17) and geometric mean diameter (GMD is 1.11) in the surface of the soil profile in the source region of Hanjiang River (LJH) are higher than Jialing River (YJS) respectively (R_0.25 is 69.81%, MWD is 1.06, and GMD is 0.47), so the soil aggregates of Hanjiang River are more stable, while the middle and lower parts of the soil profile are opposite. (2) Compared with the soil weathering in the source region of Jialing River, the source region of Hanjiang River shows a higher ratio of potassium to sodium and residual index, lower silicon and iron-aluminum ratio and leaching coefficient, stronger weathering and leaching loss of soluble elements such as calcium and sodium, besides, more aluminum rich clay minerals. The soil weathering in the source region of Jialing River is just in a transition from low strength to medium strength, while the soil weathering in the source region of Hanjiang River can reach medium intensity. Therefore, the weathering strength of the latter is much greater than that of the former. (3) According to the Soil Taxonomy, the soil developed from the loess parent material is classified as the Mot-Hap-Udic Luvisols in the source region of Hanjiang River, while it is classified as the Typ-Cal-Ustic Luvisols in the source region of Jialing River.