Based on the field investigation and experimental analysis, it was found that iron-manganese concretions, goethite(α-FeO(OH), which could indicate the soil moisture content, groundwater enrichment and paleoclimate in the profile of S4 paleosol in An village of Lantian in Xi''an. It was also found the weathering and leaching loess layer and CaCO3 illuvial layer that significantly migrated out of the argillic layer in Xi''an area. Goethite was distributed on the earth surface as yellow-brown filas and its content can be up to 3.3%. Iron-manganese concretions was brown-black spherical and crystal granular in the electron microscopy, and the content of iron and manganese was very high. Goethiteand iron-manganese concretions and celadon reducing spots distributed in the same layer of which thickness was about 0.6 m, and formed in the position of the underground water level. The material composition of goethite and iron-manganese concretions came from the migration of iron manganese oxide in the argillic horizon of S4 paleosol. According to the research, we could propose that the iron-manganese concretions, the weathering and leaching loess layer and CaCO3 illuvial layer can be used as an important index of restoring paleo-moisture. Goethite, iron-manganese concretions, the formation of weathering and leaching loess layer, the migration depth of CaCO3 concresions and red ferrunious films shows that the climate in Xi''an is subtropical, of which the annual average temperature was 15~16℃ and the average annual rainfall was between 900~1000mmin during the development period of S4 paleosol. At that time Qinling lost the function of the boundary between subtropics and temperate zone. In the development period of S4 paleosol, the depth of gravity water in soil in Xi''an area was 3.3 m, then after the soil water evaporation and transpiration consumption, the rest of the soil water content in 3.3 m depth was about 25%, and it closed to the saturated moisture content (50%) in goethite and iron-manganese concretions development layer. Soil moisture was very sufficient, and normal water cycle and water balance was positive, there were more water recharge of groundwater, as it was suitable for the development of lush forest vegetation at that time. The study it this paper has broaden the Quaternary new content and new direction and indexes proposed by us can be as standards and methods in studying soil water content, soil water form and water cycle at home and abroad