Gold nanoparticles were widely investigated as radiosensitizer under X-ray, γ-ray, e-beam.Although numbers of efforts were made in these fields, rare positive observation was reported for gold nanoparticles as radiosensitizer for heavy-ion beam.We are interested in the radiation activity of gold nanoparticles solution under irradiation of carbon ion.Here, we investigated the varation of reactive oxygen species on the concentration of gold nanopariticles under carbon ion irradiation using 2,7-dichlorofluorescein as a probe at first.Then the radiation effect of gold nanopariticles in vivo was studied.