Objective To explore the clinical effect of bedside ultrasound-guided bronchoalveolar lavage in the treatment of pneumonia complicated with atelectasis.Methods A total of 56 patients with pneumonia and atelectasis admitted to the Department of Critical Care Medicine of the People's Hospital of Jiangmen from September 2020 to September 2022 were selected.The patients were divided into control group and treatment group by random number table method,with 28 cases in each group.The control group was treated with routine treatment and bronchoalveolar lavage.The treatment group received routine treatment and bedside ultrasound-guided bronchoalveolar lavage.The changes of oxygen partial pressure (PaO2),carbon dioxide partial pressure (PaCO2),lung ultrasound score (LUS),white blood cell (WBC),procalcitonin (PCT),and mechanical ventilation time were compared between the two groups after treatment.Results Before treatment,there were no statistically significant differences in PaO2,PaCO2 and LUS score between the two groups(P＞0.05).After treatment,PaO2 of the two groups was higher than that before treatment,PaCO2 and LUS score were lower than those before treatment,and PaO2 of the treatment group was higher than that of the control group,LUS score was lower than that of the control group,the differences were statistically significant(P＜0.05).After treatment,there were no statistically significant differences in WBC and PCT between the two groups (P＞0.05).The time of mechanical ventilation in the treatment group was shorter than that in the control group,and the difference was statistically significant (P ＜0.05).Conclusion The application of bedside ultrasound-guided alveolar lavage in the treatment of pneumonia complicated with atelectasis can effectively improve the partial pressure of oxygen,promote the lung segment recruitment of atelectasis,and shorten the time of mechanical ventilation.