Abstract: OBJECTIVE To investigate the effect of synthesis of closed suction and open suction on prevent ventilator associated pneumonia (VAP) in patients with mechanical ventilation (MV), so as to provide reference for effective suction way prevent VAP in clinic. METHODS A total of 260 cases of patients with MV in the hospital ICU from Jan. 2012 to Nov. 2014 were selected. The 127 cases of patients in the control group were treated with open suction method, and 133 cases of patients in experimental group were treated with closed suction method for treatment. The VAP incidence rates of two groups were compared and data were statistically analyzed by SPSS 19.0. RESULTS The incidence rates of patients with MV in control group after 5 days and 10 days were 33.07% and 43.31%, both higher than those in experimental group 9.02% and 21.05% (P<0.05). After 5 days and 10 days MV, the clinical characters of VAP-infected patients happened like high temperature, a large amount of yellow thick viscous phlegm, both lungs moist rale, increased leukocyte, new cases of invasive shadows and pathogen was mainly Pseudomonas aeruginosa. CONCLUSION In the clinical course of patients with MV, closed suction mode could effectively reduce and delay the occurrence of VAP.