Abstract: Based on the investigation to tree roots on seawall and tests on soil antieroding and anti-watering as well as soil seeping characteristics,the paper presentS some research results as follows (A)Tree roots have a great soil holding ability and can increase soil conservation capability the index ofsoil anti-erosion and soil anti-scouring will increase with the increase of tree root quantity,especilly,of the thinner roots thinner than 1 mm in diameter.(B)Tree roots on seawall has special distributivecharacteristics.Their horizontal roots consist of 2 to 3 main side roots which develop along the seawalland only a few smaller side roots develop toward seawall. The vertical distributive depth of tree rootsis shallower, generally, the depth is 1. 0 meter or so. The deepest one will not be deeper than 1. 5 meters.(C).The main distributive layer of tree roots on seawall is restricted in upper soil layer, the influence of tree roots on sedike to soil seeping capability is restricted only in upper soil layer and there isonly a little influence to deeper soil layer.So to plant trees on seadike will not decrease the seawall stability, but can ensure its safety. Synthesizing the research results above,We should plant more andmore tree on seawall in the future on the basis of scientific design.