Objective:The purpose of this study was to investigate the clinical features and chest CT findings of Chlamydia psittaci pneumonia confirmed by metagenomic next-generation sequencing(mNGS).Methods:The clinical data and chest CT findings(the first CT and follow-up CT within one month)of 48 patients in our hospital with Chlamydia psittaci pneumonia confirmed by mNGS between August 2020 and October 2023 were retrospectively analyzed.Results:Among the 48 patients,40 cases(83.3%)had an exposure history to poultry.All cases had fever.White blood cells were elevated in 12 cases(25.0%),proportion of neutrophils was elevated in 33 cases(68.8%),and C-reactive protein was elevated in 42 cases(87.5%),with C-reactive protein>100mg/L in 29 cases(60.4%).The first chest CT scan showed that the lesion was located in the lower lobe in 41 cases,single lobe involvement in 35 cases(72.9%),all the lesions were peripheral distribution or along the bronchovascular bundle,the most common finding was consolidation(97.9%,47/48)with air bronchogram(97.9%,46/47)and halo sign(74.5%,35/47),crazy-paving appearance in 18 cases(37.5%),ipsilateral pleural effusion in 18 cases(37.5%).After adjustment of antibiotic treatment,the follow-up CT of 45 cases showed im-proved in 30 cases(66.7%),fibrous lesions in 10 cases(22.2%).The halo sign and crazy-paving ap-pearance were absorbed in 18 cases(40.0%)and 14 cases(31.1%)on the follow-up CT images.Con-clusion:The chest CT manifestations of Chlamydia psittaci pneumonia are mostly showed as consolida-tion in the lower lobes with air bronchogram sign and halo sign,often accompany with crazy-paving appearance and pleural effusion.