The excavation of foundation trench is one of the most important step of the design and construction of gravity wharf. With the vigorous development of the national infrastructure，coastlines with favorable conditions are developed and utilized rapidly，so more and more wharf engineerings have to be implemented under the complicated condition，for example，the front line of the wharf is too close to the revetment to excavate foundations with slope. To ensure the stability of revetment and satisfy the wharf construction，a higher standard is required for the support of excavation of the gravity wharfs foundation trench. This paper studies the application of tree root pile in the support of excavation of gravity wharfs foundation trench. Based on the theory of composite foundation and according to the application result of the tree root pile in the support of excavation of gravity wharfs foundation trench，the conclusion is drawn that it is feasible to adopt the tree root pile for the support of excavation of the gravity wharfs foundation trench.