The invention discloses a high-rise construction cantilever extending device. The high-rise construction cantilever extending device comprises a fixing installing plate. Fixing installing wing plates are symmetrically arranged on the upper side and the lower side of the fixing installing plate. Each fixing installing wing plate is horizontally provided with a limiting telescopic fixing module. Each limiting telescopic fixing module comprises a limiting telescopic drum horizontally installed on the corresponding fixing installing wing plate. A limiting telescopic hole is horizontally and coaxially formed in the each limiting telescopic drum. A telescopic supporting sliding rod is arranged in each limiting telescopic hole in a penetrating mode. Telescopic pulleys are evenly and symmetrically arranged on the upper side and the lower side of the interior of each limiting telescopic hole at equal intervals in an embedded mode. Limiting telescopic wheel grooves matched with the telescopic pulleys are horizontally arranged on the upper side and the lower side of the interior of each limiting telescopic sliding rod. The outer side of the left half section of each limiting telescopic drum is slidably provided with a positioning telescopic drum. The high-rise construction cantilever extending device has the advantages of being novel in structural design, efficient and stable in transmission, simple, fast and convenient to install, small in size, high in strength, and operation environent construction is achieved.