The invention relates to a scaffolding type water area continuous beam cast-in-situ supporting frame. The scaffolding type water area continuous beam cast-in-situ supporting frame comprises a bearing platform and a concrete foundation pile, wherein two rows of steel pipe piles are fixed on the bearing platform and transversely arranged on the bearing platform, the steel pipe piles on the two sides incline outwards by a certain angle according to the width of a continuous beam, and the steel pipe piles in the middle are vertically arranged. The steel pipe piles are connected through a spiral steel pipe connecting system, a transverse distribution beam is fixed to the upper end of each row of steel pipe piles, beret pieces are longitudinally laid on each transverse distribution beam and are connected through a beret piece supporting frame, a steel rail is arranged on the beret pieces, and a cuplock supporting frame is arranged on the steel rail. A model of the cast-in-situ continuous beam composed of square lumps and formworks is arranged on the cuplock supporting frame. The invention further provides the erection method of the cast-in-situ supporting frame. According to the scaffolding type water area continuous beam cast-in-situ supporting frame and the erection method of the scaffolding type water area continuous beam cast-in-situ supporting frame, the cast-in-situ supporting frame can be erected on a shallow riverbed coverage layer or basically bare and hard bed rocks, requirements of erecting the cast-in-situ supporting frame for the riverbed geological conditions are lowered, and the stability of the steel pipe piles is improved.