This study aimed to investigate the clinical and CT features associated with severe and critical COVID-19 pneumonia. Eighty-three patients with COVID-19 pneumonia, including 25 severe/critical cases and 58 ordinary cases, were enrolled. The results showed that severe/critical patients were older, had more comorbidities, and exhibited higher incidences of cough, expectoration, chest pain, and dyspnea. They also had significantly higher rates of consolidation, linear opacities, crazy-paving patterns, bronchial wall thickening, lymph node enlargement, pericardial effusion, and pleural effusion on CT scans. The CT scores of severe/critical patients were significantly higher than those of ordinary patients. Clinical factors such as age over 50 years, comorbidities, dyspnea, chest pain, cough, expectoration, decreased lymphocytes, and increased inflammation indicators were identified as risk factors for severe/critical COVID-19 pneumonia. Computed tomography findings of consolidation, linear opacities, crazy-paving patterns, bronchial wall thickening, high CT scores, and extrapulmonary lesions were associated with severe/critical COVID-19 pneumonia. The study concluded that CT plays a crucial role in diagnosing and evaluating the severity of COVID-19 pneumonia.This study aimed to investigate the clinical and CT features associated with severe and critical COVID-19 pneumonia. Eighty-three patients with COVID-19 pneumonia, including 25 severe/critical cases and 58 ordinary cases, were enrolled. The results showed that severe/critical patients were older, had more comorbidities, and exhibited higher incidences of cough, expectoration, chest pain, and dyspnea. They also had significantly higher rates of consolidation, linear opacities, crazy-paving patterns, bronchial wall thickening, lymph node enlargement, pericardial effusion, and pleural effusion on CT scans. The CT scores of severe/critical patients were significantly higher than those of ordinary patients. Clinical factors such as age over 50 years, comorbidities, dyspnea, chest pain, cough, expectoration, decreased lymphocytes, and increased inflammation indicators were identified as risk factors for severe/critical COVID-19 pneumonia. Computed tomography findings of consolidation, linear opacities, crazy-paving patterns, bronchial wall thickening, high CT scores, and extrapulmonary lesions were associated with severe/critical COVID-19 pneumonia. The study concluded that CT plays a crucial role in diagnosing and evaluating the severity of COVID-19 pneumonia.