Abstract: Piezocone penetration test（CPTU）is one of the most widely used in-situ geotechnical investigation methods for offshore wind farms in China. Its disadvantage is that the soil parameters cannot be obtained directly,but needs interpretation of the CPTU data,while the interpretation parameter is site specific. Based on an offshore wind power project in Yellow sea area located near Jiangsu province,triaxial UU,direct consolidated quick shear,triaxial CU tests and in-situ CPTU test are carried out. Then the relationship between undrained shear strength suof clayey soil and embedment depth has been proposed in this offshore area,which can be used for a quick evaluation of the undrained shear strength suof clayey soil. The theoretical calculation formula is proposed based on the Modified Cam-Clay model against the triaxial CU test results. The calibrated CPTU interpretation parameter Nktfor the strength of clayey soils ranges from 11.93 to 19.99 according to direct consolidated quick shear tests,and ranges from 8.45 to 16.68 according to triaxial test results. It is suggested that a mean value of 14.44 for Nktis taken as the interpretation parameter for the best estimate of the undrained shear strength of clayey soil in Jiangsu offshore area,which is calibrated by the direct shear test results. Finally,the relationship between the pore pressure ratio Bqand interpretation parameter Nktis established to give a better interpretation of the undrained shear strength suof clayey soil in this area. The proposed calibration methodology of establishing the correlation between Nktand Bqcan also be used for other offshore geotechnical engineering projects in the future.