The absorption efficiency of graded-index double-clad fiber lasers and amplifiers is investigated. As ray optics are no longer valid in the case of a graded index, a mode analysis method is used. The calculated results show that, in symmetric cases, absorption efficiency is higher with graded index than that with step index. In the case of an offset core, graded index can achieve the same absorption efficiency with a much smaller offset distance. Absorption efficiency for different graded-index profiles of the inner cladding is also studied and compared.