Abstract: For the deep foundation pit in soft soil areas of coastal reclamation, the composite supporting structure, which is combined by row piles, upper inner support and the lower anchor is analyzed. The mechanical behaviour of the support system is optimized by the upper inner support with more stiffness. The space of pile foundation construction is provided and the interaction between support and basement construction is reduced by the lower anchor. Preliminary studies on interaction between support and anchor are made by analyzing the field monitoring and numerical simulation. The composite supporting structure is convenient in building and has advantage of cost in soft soils, and it may provide valuable references for similar projects in the future.