Abstract: A series of soil column simulating experiments were conducted to study the effects of particle sizes of sand-gravel, mulching thicknesses, initial soil moisture content, and irrigation volume on vertical water infiltration of a Sierozen soil in the central arid zone of Ningxia under sand-gravel mulching condition. Results showed that the positive power function could be used to fit the relationship between cumulative infiltration volume and time under gravel-sand mulching conditions. The cumulative infiltration volume showed an increasing trend with the increase of the gravel-sand mulching thickness. Thickness of 15 cm gravel-sand mulching was the critical point for the increase of water infiltration rate of the tested soil. The particle size of 4.75-20 mm promoted the process of vertical soil water infiltration more than that of 20-40 mm and 2-4.75 mm. Meanwhile, the increase of initial soil moisture content significantly promoted the vertical infiltration of water, and soil moisture content in the gravel-sand mulching field was greatly higher than that in the bare soil usually. This might be one of the reasons that gravel-sand mulching increases water infiltration. The irrigation volume increasing from 59 mm to 177 mm effectively improved the process of vertical infiltration and wetting front migration. However, there was no significant change in the process of infiltration with the irrigation volume over 177 mm.