As an advanced technology in coastal and offshore engineering, wind-driven generator, the suction bucket foundation is one new offshore foundation. It is not only subjected to the long-term action of vertical load(V) induced by all weights of platform and equipment, but also is imposed by both horizontal load(H), moment(M) and torsion(T) caused by wind and wave as well as current. The judgment standard of bearing capacity behavior and practical performance of suction bucket foundation under many freedom loads have been established, which was one key of problems to appraise the stability of foundation. According to the existing results, the features of ultimate bearing capacity and failure envelopes of bucket foundation under combined loads was evaluated in the framework of the general-purpose FEM software package ABAQUS. Results indicated that the failure envelopes of bucket foundation in different loading spaces were plotted, which could be used to evaluate the stability of bucket foundation.