Purpose To analyze the correlation of pulmonary artery obstruction index (PAOI) and the cardiovascular parameters in patients with massive pulmonary embolism (MPE), and to explore the CT pulmonary angiography (CTPA) significant in radiological massive pulmonary embolism. Materials and Methods Sixty-two patients with massive pulmonary embolism confirmed by CTPA were divided into two groups according to the severity with 17 cases in high-risk group and 45 cases in non-risk group. The correlation between pulmonary artery obstruction index and cardiovascular parameters of all subjects was analyzed. Parameters in the two groups were compared including PAOI, ratio of main pulmonary artery diameter (MPAd) to the ascending main artery diameter (AAd) named rPA, and ratio of right ventricular diameter (RVd) to the left ventricular diameter (LVd) named RVd/LVd. Results Pulmonary artery obstruction index had positive correlation with the cardiovascular parameters (r=0.504, 0.543, 0.629 and 0.657, P<0.05), but negative correlation with LVd (r=-0.500, P<0.05). PAOI, MPAd, rPA, RVd/LVd and RVd were higher in the high-risk group than those in the non-high-risk group (P<0.05). LVd was lower in the high-risk group than that in the non-high-risk group (P<0.05). Conclusion CTPA can not only effectively diagnose pulmonary embolism but also assess the severity of the radiologic massive pulmonary embolism, which contributes to the clinical prognosis and treatment options.