Abstract: Offshore vane shear and penetration tests in situ were conducted in San Zao Bay near the pearl river mouth and systematic results of vane strength Cu and specific penetration resistance Ps were obtained. The specific penetration resistances and vane strength increase with the increase of depth, from which the formula, Cu = 0.0069h and Cu=0.0024Ps were derived. These conclusions provided the design bases for building the embankment in San Zao Bay. Also the method of offshore tests was improved according to the in-situ test conditions and a convenient and economical technique of offshore test for the similar engineering was given.