The bulk density (ρ_b ) and the
saturated hydraulic conductivity (K_s)are two of the main influential factors of the infiltration
property and the anti-erosion ability of soil. The studies on soil erosion rule on slope-land are mainly conducted on a runoff plot, and so the study on the
spatial variability of ρ_b and K_s on the runoff plot can accelerate or deepen the studies on rainfall-infiltration-runoff rule on the slope-land. At 120 locations on a runoff plot, 41 m×5 m, in the Liudaogou watershed, the bulk density and the
saturated hydraulic conductivity of the surface soil were measured. The stochastic distribution characteristic and the spatial variability of ρ_b and K_s on the runoff plot were detected using the traditional statistics and the geo-statistics, respectively. The result show that (1) the distribution of the bulk density and the saturated hydraulic conductivity on the plot is stochastic; (2)the result of geo-statistics analysis on the spatial variability of ρ_b and K_s shows that ρ_b has the spatial correlation characteristic, whose spatial correlation range is 7.6 m, and K_s and lnK_s don't have the spatial correlation characteristic.