Present paper deals with soil genesis and characteristics involving basic categories of scil classification. Scientific papers concerning the principle and practice on the classification of soil groups and sub-groups are manifold. However the sub-division of the basic soil categories on soil classification is still quiet different. Soil types and soil varieties are subdivided under soil groups in USSR. Soil series are recognized according to morphological features in USA. Varietaten and sub-varietaten are divided mostly on fabric characteristics in German. In pre-revolution days in China the basic units of soil classification were also divided into soil series. At present, soil types and soil varieties were used under the great soil groups. However, there is still not a suitable method for sub-division of basic categories.In detailed soil survey of the people's commune of the semi-arid plain, attemptions have been made to devide basic soil units according to genetical soil properties. The variation of soil texture in the surface horizon and the characteristics of textural profile as affected by silting of the river or irrigation are considered as one of salient characteristics in the division of basic units. The content of soil organic matter, local drainage condition governed by the micro-relief and the arrangement of textural profiles are also considered in the division of soil types. Salinity of the soil is used for the division of soil type groups, an intermediate categories between soil types and great soil groups.