Abstract: SACS model of "KANTAN Ⅲ", semi-submersible drilling platform, is established on the application of SACS. The marine environment data of some sea area with 1 500 ft depth of sea water where are the potential operation areas of "KANTAN Ⅲ" are chosen as the environment condition. The force of wind, ocean current and wave that "KANTAN Ⅲ" has to bear is calculated by SACS. The finite element analytical model for "KANTAN Ⅲ" is established by ABAQUS and the structure strength analysis of "KANTAN Ⅲ" under the environmental loading of 1 500 ft operating water depth is conducted. It can be concluded that on the premise of without large scale of change in the structure, the local restructuring and strengthening on "KANTAN Ⅲ" platform can meet the requirements of overall strength when the operating water depth is increased to 1 500 ft. This study provides the technical base of structural strength for this platform's further restructuring to meet the requirement of operating in deeper water. It also can be used as a reference by the other similar semi-submersible drilling platform on the same purpose.