Submerging tests with setting water injection holes and sensors, like moisture meters, were set up on a large-thickness self-weight collapsible loess field in Yuci District, in Jinzhong City, Shanxi Province. The results show that the diffusion pattern of the wetting front is rather complicated due to the feature of moisture spreading in test pits from the bottom up, from the top down, and from the center to the two sides because of setting water injection holes. After 52 days of immersion, the whole section of exploratory wells basically reached saturated water content in the test pits. The layout of water injection holes saved a great deal of time and cost of the experiment. The curve of volumetric water content changing with time can be divided into four stages: the early stable stage of volumetric water content, the growth and change stage of volumetric water content, the steady and extended stage of saturated water content, the late and slightly decreasing stage of volumetric water content.