Sandy field farming is a comprehensive effective technology of drought-resistant, which has been utilized in arid or semi-arid regions to vary degrees. The author presented the results of the laboratory simulating experiment conducted to investigate the process of rainfall infiltration of soil under sand and gravel mulch. The results showed that the accumulated runoff of soil under sand and gravel mulch was always higher than the one without mulch during the simulated rainfall process. It indicated that the sand and gravel mulch was propitious to reduce the covered soil surface rainfall runoff. The values of soil moisture in the soil layers with mulch at different depths were higher than those without mulch. This showed that the sand and gravel mulch could increase infiltration amounts. After a certain period of time of rainfall, the values of soil moisture with mulch at different depths would stabilize, and the values were close to each other. The soil covered with mulch would be faster than the bare soil into the steady infiltration stage.