Objective To establish the assessment method for whitening efficacy of cosmetic materials by animal model and applications． Methods Guinea pigs were irradiate with UVB for 7 days to induce skin darkening model thereafter to assess the whitening efficacy of cosmetic materials at brown part through treatment 30 days continuously． The levels of melanin index( MI) and erythemin index( EI) were analysed by Maxmeter MX18． The skin tissues were stripped， paraformaldehyde fixed and paraffin sections following the animal euthanasia． The morphological observed and image analysis were detected following Dopamine or Fontana -Masson histochemical staining． Ｒesults The MI index of skin and melanin granular in the section of guinea pig were increased significantly after UVB radiation． Following the resveratrol—arbutin blend treatment，it was showed that MI index were decreased，the melanin granular significantly inhibit by dopamine positive staining and Fontan-Masson positive staining distribution in the epidermal were decreased obviously．Conclusions The skin biophysics detecting combine histochemical staining and image analysis through UV induced skin darkening animal model，which could be used for the assessment of whitening efficacy of cosmetic materials and mechanism research of melanogenesis．