Abstract: 【Objective】To anatomy extensively “Loutu” soil profile in Guanzhong Areas, this paper try to illustrate soil-forming process of it and its classification.【Method】According to data from field investigation and experimentations in laboratory, the “Loutu” soil profile is anatomized at stratum order, soil age, structure of soil horizon and soil micromorphological features.【Result】Bt horizon is formed from 8 500 to 3 100 aB.P., BC horizon is formed from 3 100 to 2 000 aB.P., Ap horizon has formed sine 2 000 aB.P. BC horizon very resemble the Malan Loess (L1) at physical and chemical characters, structure and micromorphological features, but it has distinct difference with Ap horizon and Bt horizon. Comparability coefficient, between different horizons and Malan loess L1, is 0.8105-0.8951 in Ap horizon, 0.9051-0.9352 in BC horizon and, 0.6718 in Bt horizon, respectively. 【Conclusion】All the results in this study suggest that“Loutu” soil have Ap1-Ap2-BC-Bt-Bk-C soil profile pattern, which is caused by change of the soil forming intensity that is caused by environmental change. Ap horizon has formed since 2000 years, which infliction loessal dung and eolian dust deposition and cultivation occur simultaneously in the process of Ap horizon-formation, which is controlled the the degree and manner of human activities. BC horizon is aeolian sedimentary in relative aridity period during 3 100 - 2 000 aB.P., which has weak degree of soil forming. Bt horizon is formed during the Holocene Megathermal.

Key words: Loutu, Soil age, Human Activity, Guanzhong areas