Cofferdam reinforcement construction method under overwater island building environment

The invention relates to the technical field of building construction, in particular to a cofferdam reinforcing construction method under an overwater island building environment, which comprises the following steps: carrying out block stone silt squeezing construction; construction of backfill soil; constructing a cement mixing pile; laying a first piece of geotechnical non-woven fabric; constructing a gravel slope protection layer; reversely wrapping with a second geotextile; constructing a block stone slope protection layer; the cofferdam reinforcing construction method in the overwater island building environment has the beneficial effects that sludge at protection feet on the outer side of the cofferdam is cleaned, a block stone silt squeezing technology is adopted, double rows of cement mixing piles with the diameter being 600 mm and the distance being 450 mm are additionally arranged on the cofferdam, and gravel slope protection layers are wrapped with inner geotechnical non-woven fabric and outer geot