Abstract: Three sub-line (strain CA,CB, CS) were isolated from a human hepatocarcinoma cell line (SMMC-7721) by the single cell cloning technique.The rate of tumor-grow and the rate of spon-taneous metastasis were the highest in strain CS and the lowest (lack)in strain CB after they were inoculated subcutaneously into nude mice.The lung was the major target organ of metastasis.The morphology structure of preliminary tumor was almost the same as those of metastasis.Immuno-histochemical localization of hepatocarcinoma cell line and three sub-line were studied using the ABC method with the antibodies of HBs Ag, Keratin, AFP, H-ras,C-erb-2, P53 oncoproteins.It showed that the H-ras,C-erb-2 had a positive reaction and that the AFP, P53 a weak positive on CS strain xenografts in nude mice,while they had all negative reaction except Keratin.C-erb-2 had weak positive reaction on CB strain xenografts in nude mice.The results strongly suppory the theory of tumor cell heterogenicity.In addition,these clones,especialy strains CS could be an ideal model for the study of tumor metastasis.