Objective To investigate the differences in clinical manifestations and computed tomography pulmonary angiography （CTPA） features between primary pulmonary artery sarcoma （PPAS） and chronic pulmonary thromboembolism （CPTE）， aiming to improve the differential diagnosis of these two conditions. Methods Clinical data and CTPA signs of 28 patients with pathologically confirmed PPAS and 28 patients with CPTE were retrospectively analyzed. The differences in clinical symptoms， laboratory findings， and CTPA features were compared between the two groups. Results In the PPAS group， there were 12 males and 16 females， with a mean age of （50.7 ± 13.6） years. In the CPTE group， there were 18 males and 10 females， with a mean age of （48.7 ± 15.0） years. There were no statistically significant differences in gender and age between the two groups （P = 0.108 for gender， P = 0.602 for age）. The incidences of chest pain and cough with expectoration， along with the positive rate of neuron-specific enolase， were significantly higher in PPAS patients compared to those in the CPTE group （all P 0.05）. The incidences of chest tightness， shortness of breath， lower extremity deep venous thrombosis （DVT）， and the positive rate of N-terminal brain natriuretic peptide precursor （NT-proBNP） in the CPTE group were significantly higher than those in the PPAS group （all P 0.05）. The disease course in the PPAS group was shorter than that in the CPTE group ［5.5 （3.5， 9.6） months vs. 24.0 （9.0， 66.0） months， P 0.001］. The proportions of lesions involving the main pulmonary artery， bilateral pulmonary trunks， pulmonary valve， and right ventricular outflow tract in the PPAS group were significantly higher than those in the CPTE group. PPAS patients more frequently presented with complete filling defects， convex proximal margins， and distal pulmonary artery aneurysmal dilatation. In contrast， the CPTE group predominantly showed mural partial filling defects and flat proximal margins. The ratios of right ventricular diameter to left ventricular diameter and main pulmonary artery diameter to ascending aorta diameter in the CPTE group were significantly higher than those in the PPAS group ［（1.06 ± 0.19） vs. （0.93 ± 0.18） for the right-to-left ventricular diameter ratio， （1.20 ± 0.22） vs. （0.85 ± 0.12） for the main pulmonary artery to ascending aorta diameter ratio； all P 0.05）］. Conclusions The presence of a short disease course， prominent chest pain and cough， and filling defects that occupy the entire lumen of the central pulmonary arteries and exhibit a proximal bulging shape is highly suggestive of PPAS. In contrast， the presence of a long disease course， predominant chest tightness and shortness of breath， complicated DVT， elevated NT-proBNP， mural partial filling defect， and right heart enlargement along with main pulmonary artery dilation may strongly indicate CPTE. Fully recognizing these differences is beneficial for improving the early diagnosis of PPAS， avoiding misdiagnosis and mistreatment， and providing preliminary clues for clinical differential diagnosis.