Abstract: Objective　To explore the roles of procalcitonin in differentiating bacterial infection from other inflammatory processes and identifying bacterial species. Methods　The blood culture results of 253 hospitalized children diagnosed with sepsis from January 2010 to June 2014 were analyzed retrospectively and its relationship with PCT was also analyzed. Results　In 253 children with sepsis, the blood culture results of 124 children showed positive (49.01%). There were 71 (28.06%) cases of Gram-positive infection and 53 (20.95%) cases of Gram-negative infection. The median level of PCT in 253 patients was 1.6 (0.4-4.5) ng/ml. According to the PCT levels, all patients were divided into low level group (0.05-0.5 ng/ml, n=86), middle level group (0.5-2.0 ng/ml, n=55), high level group (2.0-10 ng/ml, n=75) and extremely high level group (10-300 ng/ml, n=37). The positive rates of bacterial culture were significantly different among different levels of PCT (χ2=69.14, P<0.01). In low level group the positive rate of bacterial culture was the lowest and in other three groups the positive rate was all above 60%. The detection rate of Gram-positive and Gram-negative bacteria was significantly different among different levels of PCT (P<0.01). In high level group the detection rate of Gram-positive bacteria was the highest while in extremely high level group the rate of Gram-negative bacteria was the highest. Conclusions　The level of PCT is helpful for the differentiation of bacterial infection from other inflammatory processes in children with sepsis and abnormally elevated PCT level may indicates Gram-negative infection.