The key design issues of the axis direction and structural form of the open terminal at south coast of Mediterranean sea are analyzed. For the axis direction，the main controlling factor is found comprehensively after considering the wind，wave and current ，and the channel，connecting structure and the impact with surrounding are also been considered，then the axis orientation is confirmed. In view of the structural form，the conventional advantages and disadvantages of the gravity type and the pile foundation type are given. Combined with the actual project，how to consider the geological conditions，operation and maintenance and new technical factors in the structure selection is explained. More importantly，the unconventional double cylinders section plan and its advantages are introduced to provide reference for similar projects.