Abstract: Objective To establish a highly metastatic model and cell line of melanoma B16 in mice by using organ selection of metastasis. Methods Histologically melanoma B16 intact tissues were subcutaneously implanted into the mice. In order to gain visible metastatic focus, BNX mice with immunodeficiency was selected according to the method of subcutaneous implantation → lung metastasis →subcutaneous inoculation → lung metastasis. In the first three generations neoplasma were removed by tumor resection when it reached 1.5 cm in diameter. In the following three generations the same steps were duplicated without resection. Then homologous cell line was established. Tumorgenicity, invasion, metastasis and morphological characteristics of the implanted tumors were studied by light microscopy, histology, cell growth curve, flow cytometry, Chromosome analysis and basement membrane invasion assay. Results Highly metastatic models of melanoma B16 were obtained after organ screening. After 3 generations in vivo, the carcinoma metastasis rate accounted to 80 percent, metastasis extent reached +++ after 45 days. While only a lower metastasis rate was found when the tumor was subcutaneously implanted absolutely without resection at the first time. But a 91.7 percent lung metastatic rate and high metastasis extent were observed again after being passaged in vivo for 3 generations after 35 days per generation. It indicated that B16-sci has similar characteristic with B16 by the assay about histology, cell growth curve, flow cytometry，Chromosome analysis and basement membrane invasion. Conclusions we had established a highly metastasis melanoma B16 model and homologous cell line， which was high, steady, and intuitionistic metastasis and have same biological characteristics of mice melanoma B16. The result provided a useful tool for the study of metastatic mechanism and treatment of carcinoma.

Key words: Melanoma, BNX mice, Selection, Metastasis, Animal model