Objective To explore application clinical diagnosis value of multi-slice CT on patients with pulmonary embolism. Methods Forty patients suspected and diagnosis to suffer from pulmonary embolism admitted by the Hospital were selected as research subjects, all of them were subject to multi-slice CT examination, the efficacy of thrombolysis and multiple test results were treated as gold standard, and the accuracy of CT examination was evaluated. Results There were 205 displays of lung artery and 69 units of embolism with the embolism rate at 34.84%, 639 units of pulmonary artery manifestations, 258 units of embolism with the embolism rate at 40.38%, the number of aorta manifestations hit 76, the number of embolism came up to 18 units with the embolism rate at 23.68%, the number of artery showed manifestations hit 1934, and the units of embolism amounted 92 with the manifestations rate at 4.76%, the units of other branch arteries hit 4587, and the number of embolism hit 40 with the embolism rate at 0.87%. Forty patients were suspected to suffer from pulmonary embolism, and finally they were clearly diagnosed to suffer from pulmonary embolism, and multi-slice CT examination results showed that 37 patients with pulmonary embolism with 3 patients being missed diagnosis were examined. The sensitivity of CT was 92.5%. Conclusion Multi-slice CT examination can have a clear show, applied on the pulmonary artery and its branches with pulmonary embolism , and the diagnosis specificity and sensitivity on pulmonary embolism are high, it casts no traumatism on patients when compared to angiography technique, and it may be the top priority for imaging examination for pulmonary embolism.