Foundation pit supporting structure and construction method thereof

The invention provides a foundation pit supporting structure. The foundation pit supporting structure comprises a plurality of supporting column piles, a plurality of cross beam sections, steel sheet piles, a plurality of stiff composite anchoring bodies and a plurality of steel pull rod cables. The multiple supporting column piles are distributed along the edge of a foundation pit at intervals and vertically arranged in a soil body on the edge of the foundation pit. The multiple cross beam sections are sequentially connected among the multiple supporting column piles in the edge direction of the foundation pit to form a row of cross beams; at least two rows of cross beams are arranged at preset intervals in the depth direction of the foundation pit; the steel sheet piles are vertically arranged in a soil body at the edge of the foundation pit, and the front surfaces of the steel sheet piles cling to the supporting column piles and the cross beam sections; the multiple stiff composite anchoring bodies are arr