Objective To explore the accuracy of CT quantitative analysis of the severity level of pulmonary embolism. Methods Patients with APE confirmed by clinic and CTPA were retrospectively analyzed. All underwent CT examination. The CT findings of patients were summarized and the severity level of PE was defined. The clinical and CTPA results were taken as the standard to calculate the accuracy rate of classification. Results The findings of plain scan of PE patients mainly were increase of local density, decrease of local density, abnormal dilatation of pulmonary arteries, posterior subpleural patches in the two lungs and strip shadows, etc.. The iodo-values of embolization areas were significantly lower than those of the control areas in most patients and the accuracy of classification of severity level was 93.0% (40/43). Conclusion Plain scan combined with related history can timely determine the risk of PE. CT quantitative analysis can determine the severity of the patient's pathogenetic condition and the accuracy is high. The clinical value of CT examination in PE is significant.