The invention relates to the technical field of water treatment and ecological repairing equipment and methods, in particular to mixed ecological filling mainly comprising modified molluscs, a composite filling sphere, a purification tank device and a preparation technology. The mixed ecological filling is prepared by mixing calcined mollusc mixed ecological filling, tea residue active carbon, zeolite, limestone, coarse aggregate, ceramsite and soft stone. Compared with the prior art, the filling, the filling sphere, the device and the technology have the advantages that a formula source of the mollusc mixed ecological filling is wide; the price is low; changing of wastes into valuables can be achieved; the requirements of modern green social sustainable development are met; the mollusc mixed ecological filling has larger specific surface area and high porosity, is light in weight, high in strength, stable in physical and chemical properties, and has no harmful effect on biological propagation; a double-layer structure of the filling sphere fixes the mollusc mixed ecological filling; the filling sphere is large in specific surface area and easy in biofilm formation and is not blocked; and the purification tank stabilization device has bondability and fluidity, is safe and stable and avoids a scouring problem.