The invention relates to the technical field of bridge construction and provides a temporary support device for a segmental girder. The temporary support device for the segmental girder comprises a limiting device, an adjustment device, an outer pipe and an inner pipe. Two long holes are formed in the outer pipe, and multiple limiting holes are formed in the inner pipe. According to the temporarysupport device for the segmental girder, the inner pipe and the outer pie are supported between the top board and the bottom board of the segment girder; when used, the limiting device is installed inone of the limiting holes and supported at the bottoms of the long holes or on the adjustment device so that the distance between the top of the inner pipe and the top board of the segmental girder is the shortest; the limiting device is pushed to move through the adjustment device, and then the inner pipe is driven to move in the vertical direction so that the top of the inner pipe is supportedon the top board of the segmental girder; the limiting device is continued to be pushed, the top of the inner pipe is adjusted to face supporting force applied by the top board of the segmental girder; the supporting strength of the top board of the segmental girder is increased; the defect that the supporting strength is insufficient when segmental girders are stacked is overcome; multilayer stacking of the segmental girders can be achieved; and the space occupancy rate is improved.