Influenced by climate, biology and soil properties, vertical soil profile showed stratification character in terms of basic physical properties. The research conducted measurement and analysis on basic physical properties of typical field in the Daxia irrigation area in Qinghai Province. The results showed that soil bulk density changed from decreasing to increasing upon soil horizon; the soil horizons in 0-40 and 90-150 cm were high porosity zones, and the others were low porosi- ty area; the saturation moisture capacity, water retention of capillary porosity and field water retention all changed from decreasing to increasing upon soil horizon featured by arithmetic progression. In addition, the research area in Daxia irrigated area showed loose structure in soil horizon of 0-40 cm, compacted in 40-60 cm, and loose again in 60-200 cm vertically.
