Characteristics of pulmonary infection after mitral valve repair in patients with metabolic syndrome (MS) and its relationships with blood pressure, blood glucose and blood lipid were investigated. Clinical data of 126 patients were retrospectively analyzed, and patients were divided into infection group (n=19) and non-infection group (n=107). The differences of MS components in patients between the two groups were compared, and the distribution of pathogens and related factors of pulmonary infection were analyzed. The postoperative pulmonary infection rate was 15.08% (19/126); the body mass index (BMI), blood pressure, fasting blood glucose (FBG), triglyceride, total cholesterol, low-density lipoprotein cholesterol, the extubation time of trachea cannula, ventilator use time, rethoracotomy hemostasis rate, sternal dehiscence rate and incidence of low-cardiac-output syndrome were higher and high-density lipoprotein (HDL-C), left ventricular ejection fraction (LVEF) was lower in the infection group than that in the non-infection group (p<0.05). The rate of postoperative pulmonary infection in patients with MS was higher than in those without MS (p<0.05). Cardiac function, BMI, FBG, HDL-C, LVEF value, extubation time of trachea cannula, ventilator use time, sternal dehiscence, rethoracotomy hemostasis and low-cardiac-output syndrome were independent risk factors for pulmonary infection after mitral valve repair in patients with MS. In conclusion, pulmonary infection easily occurs in patients with MS after mitral valve repair. Taking intervention measures according to the characteristics of pulmonary infection pathogens and predisposing factors is expected to reduce the incidence of pulmonary infection.