Foundation pit protection device

The utility model discloses a foundation pit protection device, and belongs to the technical field of building construction. Comprising a retention wall structure, a prefabricated connecting plate, a connector and a supporting piece, the retention wall structure is arranged around a foundation pit, the prefabricated connecting plate is fixed to the upper end of the retention wall structure and faces the side face of the foundation pit, the prefabricated connecting plate is sleeved with the connector, and the connector is fixedly connected with the prefabricated connecting plate. Rigid connection between the supporting piece and the retention wall can be completed without forming holes in the retention wall structure, the supporting piece is connected with the retention wall structure abutting against the bottom of the foundation pit or connected with the adjacent retention wall structure, the horizontal loading capacity of the retention wall structure can be improved, and it can be guaranteed that the structu