Abstract: Soaking tests on self-weight collapse Q3 loess with heavy section located in Lanzhou region are conducted without water injection hole and with moisture meter and heat conduction suction probe embedded. The test results indicate that multiple collapses appear in different soil layers at different depths, and the times of the collapses decrease with the increase of loess depth. The volumetric water content at different depths has different rules: the curve above 10 m in depth is made up of 6 stages, that between 10 m and 22.5 m in depth has 5 stages, and that beneath 22.5 m in depth has 3 stages. The water above 25 m in depth infiltrates easily, and the water beneath 25 m in depth infiltrates slowly because the upper loess has collapsibility inducing the compaction and air pressure among soil pores increases gradually. The cracks far from the test pit are generated by the violent motion of the cracks near the test pit. The wetting front of the self-weight collapse loess with heavy section takes the shape of an ellipse (the major axis is horizontal), and finally the eccentricity of elliptical humidification area becomes less. The soggy angle increases with the increasing supply of water source, and its variation range is 0皛55?. The vertical infiltration velocity presents the reduction tendency of power function.