Abstract: In order to explore the effects of herb roots on soil physical properties and soil nutrients, alfalfa (Medicago sativa), Bermuda grass (Cynodon dactylon) and vetiver grass (Vetiveria zizanioides), planted for three years, were used for these experiments. Taking bare plots as a contrast, soil and root samples from 0-10 cm, 10-20 cm and 20-30 cm soil layers were collected. Then the WinRHIZO (Pro.2004c) root analysis system was used to measure root parameters and conventional methods were used to measure soil physical and chemical properties. In all three soil layers, vetiver grass root parameters were excellent, especially root length density and root surface area density, for these two traits the maxima averaged 13.46 cm/cm³ and 5.75 cm²/cm³, respectively. Overall, root weight density (RWD) of alfalfa was the greatest, with a minimum average of 18.10 mg/cm³. None of the three herbs had any significant effects on soil physical properties 3 years after planting, but data for the herb plots showed that the proportion of sand particles had decreased and the proportion of finer particles (silt and clay) had increased, compared to bare CK plots. Most herbs had significant effects on soil organic matter and available potassium in most soil layers, with content of organic matter increasing and content of available potassium decreasing. However, the herbs had almost no effect on soil total nitrogen, alkali-hydrolyzable nitrogen, total phosphorous, available phosphorous and total potassium. The total potassium contents of all herb plots (3.93-4.83 g/kg) were higher than the bare plots, but the available potassium levels of all herb plots were low, especially in alfalfa. The maximum deficient number was 20.24 mg/kg. All soil nutrients had significant correlations (P<0.05) with all or some of the root parameters, and the maximum correlation coefficient was 0.833, for the relationship between organic matter and RWD.