Abstract: The research studied the effects of cadmium chloride on proto-oncogene c-myc expression in rat liver cells with Northern Dot Hybridization. The results showed: at the dose of 5μmol/kg, 10μmol/kg,20μmol/kg, cadmium chloride can induce proto-oncogene c-myc expression obviously and c-myc protein can be detected in rat liver cells with immunohistochemistry. The research infers that at certain dose,cadmium can induce proto-oncogene c-myc expression in rat liver cells.