Abstract: OBJECTIVE To investigate the effects of different doses of Shenmai injection on immune function and therapeutic effect in patients with ventilator-associated pneumonia. METHODS Ninety-three patients with ventilator- associated pneumonia were randomly divided into three groups:control group(32 cases) was given conventional treatment, low-dose intervention group(28 cases) was added with "Shenmai injection 50 mL qd" on the basis of conventional treatment, and high-dose intervention group(33 cases) was added with "Shenmai injection 100 mL qd" on the basis of conventional treatment for 14 d. The indicators included infection index(WBC, CRP, PCT), immune index(CD4⁺, CD8⁺ and CD4⁺/CD8⁺) and medical index(duration of mechanical ventilation, length of stay in the ICU, survival at 28 and 60 d) of 3 groups were compared. RESULTS After treatment, CRP, PCT, CD4⁺ and CD8⁺ in the high-dose intervention group were significantly improved compared with those in the control group; mechanical ventilation time in the low-dose intervention group and the high-dose intervention group was significantly reduced compared with that in the control group; survival rate at 28 d and 60 d was significantly improved compared with that in the control group, and the difference was statistically significant(P<0.05). CONCLUSION Shenmai injection can improve the infection index of patients with respiratory related pneumonia, has an obvious immune promoting effect, and can improve the therapeutic effect of VAP patients. And the clinical effect of 100 mL Shenmai injection is more significant.