Abstract: Terrace banks in the east Sichuan hilly area which were planted with Hemerocallis citrina for slope protection were studied together with soil in bank grids to understand root distribution characteristics and their effect on soil nutrients. Four different planting years of Hemerocallis, were used in field investigations and indoor experiments with a combination of research methods. The differences and relationships between root distribution characteristics, biomass and soil nutrients on terrace banks were analysed. With an increasing age after planting, root length, root volume, root surface area and root volume indexes increased; The root vertical distribution of 4-year-old Hemerocallis were significantly higher than in younger plants. Their values over years one to four were 185.3 cm (17,133 items), 237.5 cm², 301.2 cm³ and 158.9 cm respectively. The root system distribution levels were different due to the restrictions of the grid size. In the four different planting years of Hemerocallis, the average root biomass size sequences were: 4a>3a>2a>1a. There was different growth in different soil layers and also some differences of root biomass. The Hemerocallis root morphology not only affected the growth of the plant itself, but also affected soil fertilization. Root and soil nutrients were higher under three or four years of Hemerocallis than under 1 or 2 years of Hemerocallis, and those index in the bare plots, soil nutrient content were significantly difference between different plant ages in the same soil layer. Total N, available N and available P contents and the Hemerocallis root indicators were significantly correlated. It appears that the Hemerocallis roots have the ability to change the soil nutrients through their soil and water conservation properties. The research results could be used for choosing herbs and improving soil nutrients in the east Sichuan hilly area terrace banks and to provide a theoretical basis and practical reference value.