Abstract: The study focuses on the issue of transient seepage of water in the unsaturated vegetated soil under a time-varying rainfall condition, based on a few assumptions, the corresponding analytical solutions are obtained using multiple mathematical methods. The solutions also consider two types of typical bottom boundary conditions and arbitrary initial water content distribution patterns. Furthermore, the expressions of analytical solution for several common rainfall patterns are provided. On this basis, the reliability of the obtained analytical solutions is verified through the comparison analyses. Eventually, taking a type of vegetation cover of landfill as the object, the analytical solutions are applied to study the impacts of several factors on its bottom leakage. The results show that when the total rainfall is the same, overall, the leakage amount is larger under the pattern with a larger rainfall intensity in the early stage. For different distribution forms with equal initial total water storage, the form with a larger bottom water content leads to a larger leakage amount, but its impact mainly occurs in the early stage of rainfall infiltration. Among the four typical root shapes considered, the vegetation cover with uniform root distribution has the best effect in blocking the bottom leakage, and the exponential root shape has the worst effect. However, the effect of root shape is relatively small. An increase in the transpiration rate can reduce the leakage amount, and this effect will gradually become more significant as the rainfall infiltration process proceeds.