The sea condition of the Yushan reclamation project is complex and the soft soil is very developed. The in-situ undrained shear strength of saturated soft clay is an important geotechnical index for foundation design and foundation treatment. Therefore，the accuracy of the vane shear test is greatly improved by using the electrical vane shear instrument，selecting the appropriate operation platform and the key technology of the self-developed shipborne“static”platform，which greatly improves the accuracy of the marine vane shear test，and solves the problems of large dispersion and data distortion in the conventional offshore vane test. The technical achievements provide strong technical support for the engineering design while providing a reference for similar projects.