【Objective】To explore the value of serum procalcitonin（PCT）and percentage of neutrophils（NE%）in early diagnosis of bacterial infection in decompensated liver cirrhosis.【Methods】The clinical data of 244 in the patients with decompensated liver cirrhosis in the Department of Infectious Diseases，The third Affiliated Hospital of Sun Yat-sen University from January 2016 to June 2017 were retrospectively analyzed. According to whether complicated with bacterial infection，patients were divided into infection group（n=120）and non-infection group（n=124）. The infection group consisted of 60 cases with spontaneous bacterial peritonitis（SBP），25 cases with pulmonary infection，16 cases with bloodstream infection，19 cases with other kinds of infections. The levels of PCT，peripheral white blood cells（WBC）， peripheral neutrophils（NEUT），percentage of neutrophils（NE%）and ratio of WBC to platelets（PLT）（WBC/PLT）in each group were compared. The receiver characteristic curve（ROC）was applied and area under curve（AUROC）， sensitivity and specificity were computed. The parallel test was applied to explore the diagnostic value of PCT with NE%. 【Results】The levels of PCT，WBC，NEUT，NE% and WBC/PLT in infection group were higher than those in non-infectiongroup（P<0.05）. The levels of PCT，NE% and WBC/PLT in bloodstream infection group were higher than in non-blood? stream infection group（P<0.05）. The AUROC of the PCT was 0.947（95%CI=0.922~0.971）. When PCT was≥0.38 ng/mL， the sensitivity，specificity and Youden index（YDI）were 76.7%，97.6%，and 0.742. The AUROC of NE% was 0.806 （95%CI=0.751~0.861）. With a cutoff value of 75.0% in NE%，the sensitivity and specificity were 83.3% and 92.7%， respectively.【Conclusion】Serum PCT，with a suggesting cut-off value of 0.38 ng/mL，could be used as an marker for early diagnosis of bacterial infection in decompensated liver cirrhosis. PCT combined with NE% can improve diagnostic accuracy.