Abstract: 【Objective】 The effects of straw mulching on the spatiotemporal change of soil water in different depths of sugarcane field in Guangxi were studied to find an effective way to optimize the soil water condition in sugarcane field in Guangxi.【Method】 The experiment was conducted in a sugarcane field in Guangxi with two treatments:no straw mulching(T0)and straw mulching(TS). Rainfall data during the experiment period as well as the soil water content at 0-10 cm,10-30 cm,and 30-50 cm depth of the fields were collected through continuous dynamic monitoring to analyze the change of soil moisture and the soil physical and chemical properties under different conditions.【Result】 Straw mulching could improve the soil environment of sugarcane field and improve the soil organic matter content. The organic matter content in TS in 0-10 cm,10-30 cm,and 30-50 cm depths significantly increased by 42.8%,29.1% and 45.4%,respectively compared with T0(P<0.05,the same below). Meanwhile,straw mulching could improve the water retention ability of sugarcane soil and significantly enhance the soil moisture content. The soil water content under TS treatment was significantly increased by 10.5%,16.0% and 11.5%,respectively in 0-10 cm,10-30 cm and 30-50 cm depths. Compared with T0 treatment,TS treatment increased the soil upward water supply of 0-50 cm depth,which resulted into the more activewater movement during the water shortage.【Conclusion】 Straw mulching can reduce soil evapotranspiration and increase soil organic matter content,there by improving soil water conditions and soil environment in sugarcane planting in Guangxi,and provide a good soil environment for sugarcane root growth. It is also suggested that straw mulching is worth popularizing in sugarcane cultivated areas of Guangxi.