Abstract: OBJECTIVE To explore the influence of nosocomial infection on length of hospital stay and direct economic burden of patients so as to provide data for development of reasonable countermeasures for control of nosocomial infection. METHODS From Jan 2018 to Dec 2018,the patients who were discharged from Tangshan Gongren Hospital, hospitalized for the first time and had the complete major information were recruited as the study objects and divided into the nosocomial infection group and the non-nosocomial infection group according to the diagnostic criteria.A 1:1 case-control study was conducted by means of propensity score matching method, the influence of nosocomial infection on length of hospital stay, total hospitalization cost and average hospitalization cost was observed, and its relationship with extended length of hospital stay and high medical cost was analyzed. RESULTS A total of 497 patients were enrolled in the study, the length of hospital stay of the nosocomial infection group was 6 days longer than that of the non-nosocomial infection group（P＜0.05）; the nosocomial infection group was 3.815 times the risk of incidence of ultra long hospital stay as the non-nosocomial infection group, the attributable risk percentage was 73.788%.The hospitalization cost of the nosocomial infection group was 26,220 yuan more than that of the non-nosocomial infection group（P＜0.05）; The medical service cost, medicine cost, medical consumables cost, examination cost and laboratory test cost of the nosocomial infection group were significantly higher than those of the non-nosocomial infection group（P＜0.001）.The nosocomial infection group was 13.500 times the risk of incidence of high medical cost as the non-nosocomial infection group, and the attributable risk percentage was 92.593%.There was no significant difference in the average daily hospitalization cost between the two groups of patients, however, the average daily medical service cost, medicine cost and laboratory test cost of the nosocomial infection group were significantly more than those of the non-nosocomial infection group（P＜0.05）. CONCLUSION The nosocomial infection may result in the extension of length of hospital stay and huge direct economic loss.It is necessary to continuously improve the quality of control of nosocomial infection, relieve the patients′ sufferings and reduce the economic burden.