By analyzing the theory of “yang transforming qi and yin constituting form”，this paper explored the internal relationship between “yang transforming qi and yin constituting form” and the formation and metastasis of lung cancer from the theoretical level.By virtue of the relative attributes and infinite separability of yin and yang，the origin of lung cancer in traditional Chinese medicine(TCM) was explained from the perspective of body metabolism，and the influence of “yang transforming qi and yin constituting form” on the formation and development of lung cancer under physiological and pathological conditions was also discussed.Moreover，the paper analyzed the role of “yang transforming qi and yin constituting form” in the metastasis of lung cancer from the perspective of tumor proliferation and invasion.The waning and waxing of yin and yang between body and tumor and the formation of qi run through the whole process of the occurrence，development and metastasis of lung cancer.It is of high universality and clinical value to interpret the TCM pathogenesis of the formation and metastasis of lung cancer with the theory of “yang transforming qi and yin constituting form”.