This article probed into the internal relations and significance between differentiation of syndrome of traditional Chinese medicine (TCM) and trace elements--copper and zinc in lung cancer patients. The serum copper and zinc of 95 patients with lung cancer and 82 healthy persons were measured. According to differentiation of syndrome of TCM types of 95 lung cancer patients were divided, and the relations with their levels of serum copper, zinc and the ratio of copper/zinc compared respectively. The authors found that there were some inner links among the differentiation syndromes and levels of serum copper, zinc and its ratio. The result showed that the level of Cu/Zn ratio could reflect increase and decrease of body resistance and pathogenic factors the level of Cu/Zn ratio was more significant than that of copper and zinc. The authors suggested that the ratio of Cu/Zn could be used as the criteria of differentiation of syndrome of TCM. It is clinically significant to combine the level of copper, zinc and its ratio with differentiation of syndrome of TCM to evaluate the severity and prognosis of the patients and to direct the treatment of them with TCM.