Ne-like germanium soft X-ray lasers driven by nanosecond laser have very good applications, due to their stable output and strong intensity. The double-pass amplification mode, with a multi-layer reflective mirror added is investigated. The estimate and the experiment show that the output intensity of Ne-like germanium soft X-ray laser is enhanced by double-pass amplification. For 24mm length of double-pass amplification, the total output intensity is enhanced by 2.3 times as against that with no mirror added. Meanwhile, this mode results in quality decline of soft X-ray laser beam. So this mode is not entirely beneficial to the applied study.