Soil disintegration serves as a crucial indicator of soil erosion erodibility, significantly informing the elucidating of soil erosion mechanisms and the development of erosion models. Despite advancements in research regarding the impact of plant root on soil disintegration, the process is subject to dual influences from both root systems and soil physicochemical properties. However, comprehensive quantitative studies on the synergistic effects of these factors on soil disintegration remains elusive. This study utilized undisturbed soil samples under five different land use patterns within the Wangmaogou watershed as the research object. By conducting disintegration experiments, the soil disintegration parameters are determined. The analysis was conducted to explore the correlation and identify significant factors influencing these parameters in relation to root systems and soil physicochemical properties. Eventually, this quantitative approach aimed to elucidate the mechanisms driving changes in soil disintegration. The findings revealed the following conclusions: (1) The comprehensive analysis of disintegration rate, disintegration ratio rate, and the amount of disintegration revealed a distinct trend in soil vulnerability across land use patterns. grasslands exhibited the lowest degree of disintegration, followed by sloping arable land, then terraced fields, with orchards demonstrating greater disintegration characteristics, and dam lands showing the highest degree of disintegration. (2) Using soil physicochemical properties and root characteristics as categorical variables, this study utilized variance partitioning analysis (VPA) and partial least squares path analysis (PLS-PM) to explicate the contributions of soil physicochemical properties and root characteristics, along with their synergistic effects on soil disintegration. The quantitative relationships among these factors were also analyzed. Findings revealed that within root- laden soil, the direct effect of roots on soil disintegration surpassed the indirect effects, accounting for a 16% contribution, a figure marginally lower by 2.4% compared to the direct contribution of soil physicochemical properties, but this was 62.5% greater than the combined synergistic effect of the two factors. Under different land use patterns, The alterations in soil disintegration capability were primarily driven by the direct influences of soil physicochemical properties. (3) The Spearman correlation analysis and Redundancy Analysis (RDA) revealed that among the root factors, RLD (root length density) exhibited the highest correlation with soil disintegration, while silt content was the most significant soil factor. Among all environmental factors, the effect of RLD was the most pronounced. Under different land use patterns, the principal determinants that govern the soil disintegration properties are found to be distinct. These research results can provide reference for the study of soil disintegration and the elucidation of erosion mechanisms under ecological construction conditions in the loess hilly and gully region, which possess significant implications for ecological restoration and the maintenance of ecological functions in the ecological fragile regions of the Loess Plateau.