Objective To describe the distribution and pathogen of postoperative pneumonia(POP) in patients, understand the characteristics of POP of surgical patients in a tertiary-first class hospital, and explore the risk factors for POP. Methods Occurrence of POP in surgical patients from 2014 to 2018 was analyzed with descriptive epidemiological method. Results From 2014 to 2018, case incidence of POP in this hospital was 0.19%-0.25%, with an average incidence of 0.22% and case fatality rate of 17.62%. There was no significant difference in incidence and case fatality rate of POP among different years, seasons, and months. Department of cardiac surgery, neurosurgery and thoracic surgery were the top three departments of POP incidence in this hospital. Incidence of POP was the highest in infants< 1 years(1.36%) and lowest in patients of 30-39 years old (0.01%). Incidence of POP decreased firstly and then increased with age. Incidence of POP in male was higher than that of female (χ²=52.37,P<0.001). 76.52%(163/213) of isolated pathogens from patients with POP were Gram-negative bacteria, mainly Acinetobacter baumannii (27.23%), Pseudomonas aeruginosa (14.55%), and Klebsiella pneumoniae (12.21%), detection rate of multidrug-resistant organisms in POP was 30.99%(66/213). Conclusion Incidence of POP is low in this hospital, department of cardiac surgery, neurosurgery and thoracic surgery are with high incidence of POP. Infants, elderly patients and male patients are high risk population of POP, the main pathogens of POP are Gram-negative bacteria with high antimicrobial resistance rate.