Subject and method: 40 patients with VAP treated at Intensive Care Units, 108 Military Central Hospital from August 2019 to April 2020, was randomly divided into 2 groups: The study group with 20 VAP was treated and stopped antibiotics when PCT was lower 0.5ng / ml or decreased 80% of peak value (PCT group) and the control group with 20 VAP was an antibiotic regimen selected by the treating physician.