Deep foundation pit structure and construction method thereof

The invention relates to the technical field of foundation pit construction, in particular to a deep foundation pit structure and a construction method thereof.The deep foundation pit structure comprises a foundation pit body, a plurality of supporting plates are evenly arranged on the inner wall of the foundation pit body, a fixing plate is arranged at the edge of the foundation pit body, and the fixing plate comprises a horizontal part and a vertical part which are integrally arranged; the horizontal part is arranged on the ground, the vertical part is arranged in the foundation pit body, an inserting rod used for fixing the horizontal part is arranged on the horizontal part, the inserting rod is inserted in the ground, a mounting part is arranged on the side, away from the ground, of the vertical part, and an auxiliary rod is arranged on the side, away from the foundation pit body, of the mounting part. An auxiliary plate is arranged on the side face of the supporting plate, an auxiliary groove is formed i