Object: To study the application value of multi-slice spiral CT pulmonary angiography (CTPA) in the diagnosis of pulmonary embolism (PE). Methods: CT pulmonary angiography data of 31 patients with pulmonary embolism were studied, and the direct and indirect signs of CTPA were analyzed. The direct and indirect signs of were analyzed. Results: 31 cases of in patients with pulmonary artery trunk 2, left and right pulmonary artery in a total of 23, including bilateral pulmonary embolism in 3 cases, lobar artery of 49, 148 branches of the segmental artery, sub segmental artery and arterial branch 123, to the right pulmonary artery, a total of involving 345 branch of pulmonary artery and its branches. The direct CT signs of pulmonary embolism: central filling defect, eccentric filling defect, filling defect in the inner part of the uplift, mural filling defect, completely filling defect. Indirect signs: uneven distribution of pulmonary blood vessels, thinning of the pulmonary veins, pulmonary infarction; pulmonary artery pressure signs, such as increased width of the main pulmonary artery and the left and right pulmonary arteries, and the right ventricular enlargement. Conclusion: More slice spiral CT pulmonary angiography in the diagnosis of PE is fast, safe, no invasive, high sensitivity, select the appropriate scanning parameters and the method of image reconstruction can clearly show the shape and scope of the site of pulmonary embolism and embolus, timely guidance to clinical diagnosis and treatment.