Abstract: Objectives: To investigate the preliminary application of spectral CT on the differential diagnosis between squamous cell carcinoma(SCC) and adenoid cystic carcinoma(ACC) of the primary central airway tumors by spectral CT scan and multi-parameter quantitative measurement. Methods: Choose the patients who were found with central airway tumors and without any treatment to take the gemstone spectral CT examination. We choose the patients who can comply with the conditions of enhancement to take plain scan and enhancement scan in arterial phase on GSI mode. All the data was processed by GSI Viewer software. The lump substance composition was selected as region of interest, measuring iodine concentration, water concentration and corresponding CT value of 40 ke V, Then calculate the corresponding slope of spectral curve, 26 patients were divided into SCC group and ACC group. Independent samples t test was used to analysis whether the parameters of plain scanning and arterial phase scanning have statistical significance. Results: Plain scan: Corresponding CT value at 40 ke V, energy spectrum curve slope, calcium content of SCC group was higher than those of ACC group, the difference was statistically significant(P<0.05), there was no significant difference in the water content in the two groups(P>0.05). Arterial phase enhanced scan: CT value at 40 ke V, the slope of the energy spectrum curve, iodine content of SCC group were higher than those of ACC group, the difference was statistically significant(P<0.05), there was no significant difference between the water content(P>0.05). Conclusions: Spectrum CT imaging can provide more quantitative and qualitative information for central airway primary tumor diagnosis. It can be used as a new method for diagnosis, and has certain clinical application value.