With the accelerating process of urbanization, various kinds of unconventional concrete structure increases day by day. According to the Monitoring work achievement of the Memorial Hall for the Battle of crossing Yangtze River, the support system is a new kind of formwork support system that is made up of profiled bars and steel tubes. This support system with high bearing capacity and rigidity is suitable for all kinds of complex structures. The interaction mechanism between cantilever structure and support system and the force distribution rule of the members in structure and support system were studied in the paper. On based of above researches the time-varying model which is made up of the structure and high assembled formwork support system was put up to calculate the bearing capacity of the support system.