CaVSn:YIG was irradiated with 47 MeV/u carbon ions at Heavy Ion ResearchFacility of Lanzhou(HIRFL). The irradiation effects were studied by Mossbauerspectroscopy and positron lifetime measurement. The irradiation resulted in anisotropic distribution of the hyperfine magnetic field. No amorphous area Wasdetected in irradiated samples. The defects induced by irradiation were foundincreasing with the electron stopping power.