The invention discloses a stone filling and island building construction bearing platform method for an underwater stone abrupt slope area. Grouting steel sleeves, thick steel bars and cement-water glass double-liquid slurry are used for forming composite small anti-slide piles to resist an island building body from sliding down into a river, so that the island building area and the backfill engineering quantity are reduced, the construction period and the construction cost are saved, and the construction safety can further be ensured. The grouting steel sleeves are not taken out, so that thelateral stability of a bearing platform foundation pit in the later period is improved, and foundation pit excavation safety is guaranteed. Curtain grouting of the periphery of a foundation pit and bottom sealing grouting of the bottom of the foundation pit are carried out by adopting the cement-water glass double-liquid slurry, bearing platform foundation pit water stopping is carried out, the water stopping effect is good, secondary water stopping is not needed in subsequent bearing platform foundation pit excavation, and maximization of economy, safety and practicability is achieved. Compared with the prior art, large equipment is not needed, a large number of steel structures are not needed, the structure is safe, the procedure is single, and economical efficiency is good. The problemthat the bearing platform in the underwater stone abrupt slope area is difficult to construct is solved.