Objective To explore risk factors and preventive measurement for early onset VAP(EOP) and late onset VAP(LOP) of elderly patients in the ICU.Methods 189 elderly patients in ICU were divided into EOP group and LOP group, and risk factors of the two groups were analyzed.Results The incidence rates of EOP and LOP were 32.18% and 51.96%.EOP occurred in GCS score from 8 to 12, and LOP in GCS score from 4 to 7.The independent risk factors for EOP group were high APACHE II score, COPD history and prolonged mechanical ventilation time;while for LOP were COPD history, prolonged mechanical ventilation time, albumin<30 g/L and consciousness disorder.The common risk factors of the two groups were prolonged mechanical ventilation time and COPD history.The pathogenic bacteria of the two groups were mainly gram negative bacillus.Conclusion The incidence of VAP in elderly patients is high and various factors contributed to VAP.The incidence of VAP in elderly patients can be reduced by avoiding risk factors for LOP and taking early diagnosis.