Abstract: Effect of filtration on composition, microstructure and mechanical properties of cobalt-base superalloy K640S was investigated. The results show that the filtration treatment can effectively decrease the content of O and N elements and increase creep life of the recycled superalloy K640S remarkably at the condition of 815°C , 205 MPa. But, the filtration treatment has no influence on the tensile property of the superalloy. The microstructure of the virgin superalloy K640S and the filtration treated recycle alloy consist of the same skeleton-like carbides in form of M23C6 and the flake-like carbides in form of M7C3 distributed among the dendrites and at grain boundary in r matrix. From the present data, it is suggested that superalloy K640S can still offer payoffs as a structural material in gas turbine application after filtration recycle.