Fresh water supplied are often limited in mainland China, reducing agricultural productivity. However the use of straw mulch is the main management technique for agronomic water saving. This paper investigates the movement of soil water under straw mulch compared to a non-mulch test plot. Results demonstrated that straw mulch effected soil water movement primarily during drought periods and throughout shallow soil(i.e. depths of less than 200 cm). The soil moisture and soil water potential at the mulch test plot in drought period are both higher than that of contrast test plot, and along with increasing soil depth, the straw mulch effect weakens. When evaporation is dominated by surface evaporation, straw mulch will effectively restrict the evaporation of soil water; when evaporation dominated by vegetation transpiration, the straw mulch promotes the transpiration of vegetation. In drought periods, straw mulch is not effective for deep soil water infiltration, but is advantageous for soil water utilization of mid-and shallow-soils(0-120 cm), however the infiltration speed rate of straw mulch point during high water period is higher than that of contrast plot. This paper highlights the importance of good management practices of agricultural land in order to limit soil water losses, which is essential when water is such a limited resource.