To observe the clinical effects of Maimendong Decoction combined with Weijing Decoction in the treatment of patients with lung cancer with yin deficiency and lung heat syndrome,and to explore the possible mechanisms.Methods:A total of 104 patients with lung cancer admitted to the Binzhou Hospital of Traditional Chinese Medicine from June 2017 to June 2018 were selected as the research objects,and were randomly divided into a control group and an observation group according to random number table method,with 52 cases in each group.Patients in the control group were given chemotherapy intervention,and the patients in the observation group were given modified Maimendong Decoction combined with Weijing Decoction on the basis of chemotherapy intervention.The Short-term therapeutic effects,quality of life,Th1/Th2 cytokine content and peripheral blood related factor levels,and the incidence of toxic and side effects were observed.Results:The short-term therapeutic effects of the observation group and the control group were 65.38% and 38.46% respectively,and the short-term therapeutic effects of the observation group was better (P<0.05).After treatment,the quality-of-life FACT-L scores of the observation group were higher than those of the control group and the observation group before treatment (P<0.05).The immune function of patients in the control group decreased after chemotherapy intervention,while the immune function of patients in the observation group was improved.The levels of Th1 related cytokines IL-2 and IFN-γ in peripheral blood were significantly higher than those in the control group,and the levels of Th2 related cytokines IL-4 and IL-10 were significantly lower than those in the control group (P<0.05).The serum levels of VEGF,COX-2,cyfra21-1 and CA19-9 in the observation group were significantly lower than those in the control group (P<0.05).The toxic and side effects in the observation group were significantly reduced compared with the control group (P<0.05).Conclusion:The effects of Modified Maimendong Decoction combined with Weijing Decoction in the treatment of lung cancer patients with heat syndrome of yin deficiency and lung cancer is obvious in enhancing efficacy and toxicity reducing,which is conducive to improving the quality of life.The mechanisms may be related to the correction of Th1/Th2 cell immune imbalance and the inhibition of VEGF and cox-2 expression to play a role of resistance to blood vessels.