The void caused by sand leakage in the backfill area behind a cylindrical gravity wharf has a great influence on the safe operation of the wharf. The ground penetrating radar（GPR）method has unique advantages in disease detection. On the basis of the characteristics of cylindrical gravity wharf engineering and the working principle of GPR，this paper performs forward modeling of the engineering model by programming calculations on matlab. Then，it uses engineering examples to detect the abnormal areas of sand leakage with two media，i.e.，cement slabs and hydraulic fill sand，and those of sand leakage with three media，i.e.，cement slabs，hydraulic fill sand，and gravel. Moreover，the study analyzes the characteristics of the electromagnetic response to delineate abnormal disease areas and verifies the detection effect of GPR with borehole and borehole TV imaging and seismic imaging methods. Practical application shows that GPR can be effectively used for the delineation of abnormal disease areas caused by sand leakage in the backfill area of the cylindrical gravity wharf. The research results can provide a reference for disease detection and treatment of similar projects.