The fixing piece comprises a first buckle, a second buckle and a connecting plate connected between the first buckle and the second buckle, the first buckle or the second buckle is an arc-shaped plate-shaped component with a notch, and the first buckle and the second buckle are sequentially connected with the connecting plate to form an S shape. The fixing structure comprises a column rib connected to the foundation bottom plate and a water stop strip connected to the joint of the lower end of the column rib and the foundation bottom plate. Connecting and fixing are conducted through the fixing pieces, the connecting plates can be prefabricated in advance corresponding to the water stop strips, and rapid construction is facilitated; the vertical width of the connecting plate is manufactured corresponding to that of the water stop strip, so that the whole water stop strip can be uniformly stressed, and fixed connection and subsequent pouring construction of the water stop strip and thereinforcing steel bar are facilitated; the first retaining ring and the second retaining ring are integrally connected or detachably connected, the integrated connection is suitable for large-batch construction, and the detachable connection can be adjusted according to site conditions, so that the adaptability is higher.