Relative doses of 75MeV/u 12C ion beam after passing through different thickness of degraders were measured with the double ionization chamber method. The degrader’s thickness as then equalized to penetration depth of the beam in water and its Bragg curve was obtained. The measured Bragg curve is compared with that calculated based on a model set up by the authors. Meanwhile

the inactivation effect of the ion beam passing through different thickness of degraders on melanoma （B16）cells was measured

and the corresponding survival fraction data for B16 cells were acquired.