According to the sedimental condition and the thickness of overburden on sea bottom of Weihai bay, Shandong province, sonic prospeding method is selected to survey the direction and location of Shendaokou Fault. The result shows that the profiles are well and the method is suitable for prospecting structure in shallow strata on sac bottom. Conbining with the submarine topographical data, the result is tested, and the precise crientation of the fault on sea bottom has been done successfully.