The invention relates to a flexible multi-point forming device for plates. The device comprises a hydraulic container with an opening, a flexible diaphragm mounted at the opening, a pressure regulating unit and multiple pressurizing units, wherein the flexible diaphragm seals the inside of the hydraulic container to form a hydraulic cavity, the pressure regulating unit is communicated with the hydraulic cavity, and the pressurizing units are arranged movably relatively to the flexible diaphragm. The pressurizing units move towards the direction of the flexible diaphragm, so that a to-be-formed plate arranged between the flexible diaphragm and the pressurizing units is deformed synchronously along with deformation of the flexible diaphragm towards to the inside of the hydraulic cavity until the to-be-deformed plate is formed in a preset shape. Since the flexible diaphragm can provide matched real-time adjustable and uniform normal acting force, effective normal constraint on the to-be-formed plate is formed, vacant regions in the forming process of cambered stamped parts are eliminated basically, and corrugation of the plate can be effectively inhibited. Formed workpieces are good in surface quality, uniform in thickness and free of defects such as pressing marks.