Soil-pile interaction problem is very important to understand entire stability of offshorewind turbine(OWT) pile foundation. OWT pile foundations should support frequently significant overturing moment due to wind, current and storm surge. These severe external loads make large overturning moment and horizontal displacement around pile top penetrated into ground. In this paper, the behaviors of OWT pile foundation, which is modeled using existing pile design method and FEM, are investigated, And also the case studies of reliability analysis in terms of OWT foundation types are compared. In conclusion, it was reconfirmed that engineering judgement whenanalyzing OWT soil-pile interaction is very critical issues because there exists large uncertainties in pile design variables.e. These severe external loads make largeoverturning moment and horizontal displacement around pile top penetrated into ground. In this paper, the behaviors of OWT pile foundation, which is modeled using existing pile design method and FEM, are investigated, And also the case studies of reliability analysis in terms of OWT foundation types are compared. In conclusion, it was reconfirmed that engineering judgement when analyzing OWT soil-pile interaction is very critical issues because there exists large uncertainties in pile design variables.