Aimed at the five land use patterns of Liudaogou catchment at the northern loess plateau,the paper conducted the experiment of topsoil infiltration and specific penetration resistance. It developed a simple infiltration model for the topsoil based on water balance principle and theory of stable infiltration. The unsaturated infiltration coefficient of topsoil was estimated by combining the results of experiments with model calculation. The results indicated that the correlation coefficient between infiltration rate and topsoil specific penetration resistance is higher than 0.93;the number grade of unsaturated infiltration rate of topsoil is 10-5 m/s; the sequence of infiltration rate of the five land use patterns from large to small is alfalfa (on slope land) ＜ grassland (on slope land) ＜ grassland (on alluvial plain) ＜ farmland (on alluvial plain) ＜ sandy loess (nudation)。The result can provide the theory and reference for the study on soil hydraulic property and the development of infiltration model.