Abstract: OBJECTIVE To explore the clinical characteristics of nine cases of clustered Chlamydia psittaci pneumonia under the COVID-19 pandemic. METHODS Total of nine cases diagnosed with C. psittaci pneumonia during Dec 2020 were enrolled in the study, of whom eight cases were treated in the Department of Miyun District of Peking University First Hospital and one case were from TCM Hospital of Beijing Miyun Traditional Chinese Medicine Hospital. The clinical data of the patients were retrospectively analyzed, and the clinical characteristics of the disease and treatment were summarized. RESULTS The onset time of nine patients was concentrated, and all of them had activities or living history in pigeon breeding area. All patients had different degrees of fever, 77.80% of whom were high fever, accompanied by cough and expectoration. The white blood cell count was normal and the neutrophils were increased. C-reactive protein level in 8 cases was increased and D-dimer was elevated in six cases. Chest CT scanning showed high-density consolidation in unilateral lungs, with bronchial inflatable signs, especially in lower lungs, but bilateral lung changes were not common. One death was reported as multiple variations in ground-glass opacity of bilateral lungs. Eight patients were treated and recovered with no observable inflammatory lesions and esidual fibrosis. Two patients’ specimens were detected with C. psittaci nucleic acid by metagenomics next-generation sequencing（mNGS） technology. Seven patients underwent serum antibody test for C. psittaci, all of which were positive. Six patients were under respiratory tract pathogenic testing, all of which were the combined infection of Klebsiella. Quinolone antibiotics were used in the treatment of eight patients, either alone or in combination with other drugs. Two patients were treated with tetracyclines. Eight patients were cured, and one died clinically. CONCLUSION Patients should be inquired their contact history in detail when encountering an unexpected clustered outbreak of pneumonia. The mNGS is efficient in identifying the pathogenic bacteria, which can help to reduce the burden of disease ultimately. Except for tetracyclines, quinolones have shown good therapeutic effects in the treatment of C. psittaci pneumonia.