For the case that the gravity wharf has large load increasing after the upgrading and rebuilding,the structure stability and the bearing capacity can't meet the specification requirements.The method of adding pile foundation and simply supported slab platform to form the unloading platform is proposed,which can reduce the earth pressure.The calculation result shows that the unloading platform has significant effect on improving the stability and bearing capacity of the structure and reducing the foundation stress.The advantages and disadvantages and adaptability of this structure are studied after.