High-precision system for rapidly lowering support in cofferdam and construction method thereof

The invention belongs to the technical field of building construction, particularly relates to a high-precision system for rapidly lowering an inner support of a cofferdam and a construction method thereof, and aims to solve the problems that hoisting is troublesome, the sight is blocked, hoisting is unsafe, the inner support is easy to shake in the placing process, and if positioning is not carried out, the inner support can be rapidly lowered. In order to solve the problems that in the prior art, steel piles are prone to colliding with the steel sheet piles, and the steel piles are prone to being stuck in the lowering process, the following scheme is provided that the device comprises a plurality of steel casings and a plurality of supporting frames used for supporting the steel sheet piles, and a plurality of connecting columns are fixedly arranged on the inner walls of the supporting frames; a plurality of first guide sleeves and semicircular cylinders are fixedly arranged above the multiple connecting co