Space truss supporting platform, system and method for ultra-deep underground diaphragm wall

The invention discloses a space truss supporting platform, system and method for an ultra-deep underground diaphragm wall, the platform comprises a truss head section and truss standard sections, the truss head section and the truss standard sections are detachably connected, and the truss head section and the truss standard sections are adjacently arranged between the truss standard sections. The system comprises a space truss supporting platform and a reinforcement cage, and the reinforcement cage is connected with the space truss supporting platform. The method comprises the steps that the end I-shaped steel and the bottom face reinforcing mesh are welded; placing a bottom surface reinforcing mesh in place; temporarily fixing the space truss supporting platform and the bottom surface reinforcing mesh; inclined ribs and longitudinal supporting trusses are installed on the two sides of the space truss supporting platform; mounting a top surface reinforcing mesh; temporarily fixing the space truss supporting