Abstract: As an systemic inflammatory mediator, procalcitonin (PCT) is one of the new inflammatory markers which have been studied recently. Compared with other biological markers, PCT has higher sensitivity and specificity, and can be more effective to distinguish bacterial infection from other inflammatory processes. PCT is not only a good indicator screening for infectious diseases, because of serum PCT having different concentrations in viral infection, bacterial infection (including Gram-positive bacteria and Gram-negative bacteria), fungal infection or other atypical pathogens infection, it is also effective index that can identificate different pathogenic bacteria infection. The initial serum concentration of PCT has some guiding significance for antibiotic therapy, and in the whole course of treatment, it is important to monitor and manage PCT for evaluating if continuing or discontinuing antibiotics. Moreover, the dynamic changes of PCT are of great significance in evaluating the severity and prognosis of infection, and judging the treatment effectiveness. At the same time, PCT-guided antibiotic treatment can reduce the use of antibiotics, shorten the hospitalization time of patients and reduce the hospitalization costs, thereby reducing the incidence of antibiotic resistance, social cost and increasing social benefit in the whole. Although there were many studies about PCT in different types, different experimental design methods and that had selective biases, the cut-off values or threshold of PCT is difficult to define in identification of infection types, assessment of disease severity and prognosis. Up to date, evidence of very low to moderate quality, with insufficient sample power per outcome, does not clearly support the use of procalcitonin-guided antimicrobial therapy to minimize mortality, clinical severity,reinfection or duration of antimicrobial therapy of patients. It still needs further study.This artical reviewed the clinical application and research progress of procalcitonin.