Large deep foundation pit supporting system and construction method thereof

The invention provides a large deep foundation pit supporting system and a construction method thereof. The large deep foundation pit supporting system comprises supporting piles arranged on the periphery of a foundation pit, waist beam structures are fixed in the height direction of the inner side walls of the supporting piles, anchor cables are connected to the waist beam structures, and the anchor cables are anchored in a peripheral foundation of the foundation pit; a foundation pit bottom sealing layer is fixed to the inner bottom of the foundation pit through anti-floating piles, and a structural foundation layer is arranged on the top of the foundation pit bottom sealing layer. Cap beams are arranged at the tops of the supporting piles, intercepting ditches are arranged on the peripheries of the tops of the cap beams, apron slopes are arranged on the peripheries of the intercepting ditches, and waterproof curtains are arranged on the peripheries of the apron slopes and extend into the foundation on the