Objective: To investigate the efficacy of fiberoptic bronchoscopy in the treatment of severe pulmonary infection and its effect on pulmonary function and inflammatory factors. Methods: A total of 122 patients with severe pulmonary infection treated in our hospital from May 2017 to May 2020 were selected and were randomly divided into an observation group (n=61) and a control group (n=61). The control group was treated with routine anti-infective therapy for 10 days. On the basis of the control group, the observation group was treated with fiberoptic bronchoscope for 3 times/week for 10–20 min each time, and 10 days was a course of treatment. The effective rate of treatment, time of symptom disappearance, the level of inflammatory factors, blood gas index and pulmonary function before and after treatment were compared between the two groups. Results: The total effective rate was significantly higher in the observation group (88.52%) than that in the control group (73.77%). Time of symptom disappearance in the observation group was significantly shorter than that in the control group. The levels of white blood cell (WBC), procalcitonin (PCT) and hypersensitive C-reactive protein (hs-CRP) in the observation group were significantly lower than those in the control group. The oxygen saturation (SaO2) and arterial partial pressure of oxygen (PaO2) were significantly higher in the observation group than those in the control group, while the partial pressure of carbon dioxide (PaCO2) was significantly lower than that in the control group. The maximum expiratory volume (MMV), total lung capacity (TLC), forced expiratory volume of 1 s (FEV1) and maximum mid-expiratory flow (MMEF) were significantly higher in the observation group than those in the control group (P<0.05). Conclusion: Fiberoptic bronchoscopy can improve the clinical effect, shorten the time of symptom disappearance, reduce the level of inflammatory factors, improve blood gas index as well as lung function in patients with severe pulmonary infection.