The study analyzed clinical features and chest CT findings in 42 patients with pneumonia caused by Chlamydia pneumoniae confirmed by metagenomic sequencing. Of the 42 patients, 25 (59.5%) had a fever, 26 (61.9%) had a sore throat, 30 (71.4%) had a cough, and 27 (64.3%) had expectoration. Other symptoms included generalized myalgia in 11 (26.2%) and headache or dizziness in 10 (23.8%). Laboratory tests showed mildly elevated white blood cells in 12 (28.6%), neutrophils in 10 (23.8%), and elevated CRP in 21 (50.0%), with 6 (14.3%) exceeding 100 mg/L. In the initial CT, lobular involvement was typical in 16 (55.2%), one lobe in 20 (69.0%), lower lung in 19 (65.5%), with a halo sign in 25 (86.2%), centrilobular nodules in 23 (79.3%), and bronchial wall thickening in 20 (69.0%). In the middle to late stage, lobular pneumonia appeared in 23 (76.7%), with a similar distribution and signs such as a halo in 21 (70.0%) or bronchial thickening in 24 (80.0%). There were differences in imaging between stages, with a nodular patchy pattern may serve as an ultra-early marker for early intervention.