The invention discloses a freezing supporting device and method for a large thin-wall member, and belongs to the technical field of mechanical processing supporting. The freezing supporting on the large thin-wall member is achieved through a freezing system and an auxiliary system, wherein the freezing system comprises a heating source, a freezing source, a flexible membrane, a supporting plate and the like, and the auxiliary system comprises a rotary device, a moving plate and a guiding rail. The device and the method have the advantages that ice with a certain thickness is formed on the supporting side of a processing area, a work piece is supported through the ice, and the ice is used for supporting in the processing to achieve a moving supporting effect. The device and the method havethe advantages that the supporting structure is simplified, the cost is low, a machine tool is not contaminated, the use is convenient, the effect of tightly clamping the work piece is achieved, clamping force and clamping deformation are not generated, the supporting surface is not scratched, the supporting surface is protected and supported, the moving supporting effect is achieved, the device can be used for large work piece supporting, and the curved surface supporting of any curvature rate can be achieved.