Pit support structure and construction method thereof

The invention discloses a pit support structure and a construction method thereof. The pit support structure comprises a pit support pile, a water-stopping curtain, an earth berm and a horizontal lattice steel support. The pit support pile is a cast-in-place reinforced concrete bored pile. The water stopping curtain is a row of meshed cement mixing piles and disposed on one side, corresponding to the periphery of a pit, of the pit support pile. The horizontal lattice steel support is disposed between a cap beam and a reinforced concrete bracket.