Abstract: In order to study the plant growth, pull-out resistance and shear strength of root-soil composite of vegetation concrete slope protection substrates with different proportions, four levels for each of cement and straw fibers were selected to carry out indoor herbaceous plant planting experiments. The results showed that the alfalfa growth was inhibited by increasing cement content, plant height, root length and stem diameter generally decreased, while the increase of straw content could promote the growth of alfalfa. With the increase of cement content, the biomass of Alfalfa increased first and then decreased, and the biomass of substrates reached the maximum at 7% cement content. The pull-out resistance of Alfalfa rhizome decreases gradually with the increase of straw content. The The tensile resistance and pulling resistance of Alfalfa rhizome increases first and then decreases (2% is the highest), of which 2%, 4% is straw, 5%, 7% and 9% cement content is the substrates. The tensile pulling resistance of Alfalfa rhizome are obviously higher than those of other proportions; the shear stress of root soil increases first and then decreases with the increase of straw content. The shear stress reaches the maximum when the content of straw is 7% cement. The results of this study might provide a reference for further exploring the interaction mechanism between plant roots and soil and for optimizing the performance of vegetation concrete substrates.