Shaped steel frame upward-returning formwork system

The shaped steel frame upward-returning formwork system comprises an outer formwork structure and an inner formwork structure. The horizontal section of the outer formwork structure is rectangular, and the outer formwork structure is arranged along the outer side line of a to-be-poured wall. The inner formwork structure is arranged in the outer formwork structure, and the distance between the inner formwork structure and the outer formwork structure is matched with the thickness of a wall to be poured. The inner formwork structure comprises an inner corner formwork structure unit and an innerside formwork structure unit. The four inner corner formwork structure units are correspondingly arranged at the positions of internal corners of a to-be-poured wall. The number of the inner side diestructure units is four, the inner side die structure units are detachably connected between the adjacent inner corner die structure units respectively, and the outer side faces of the inner side diestructure units are flush w