Objective To study the clinical value of multi-slice spiral CT (MSCT) combined with tumor markers in the differential diagnosis of cancerous and tuberculous pleural effusion. Methods The MSCT imaging data and data of tumor marker detection of 40 patients with cancerous pleural effusion (observation group) and 50 patients with tuberculous pleural effusion (control group) were analyzed retrospectively. The CT value, levels of CA199, CA153 and CEA in pleural effusion were compared between the two groups. Based on the pathological results, the sensitivities and specificities of MSCT, tumor markers alone and combined in the diagnosis of character of pleural effusion were compared. Results The typical MSCT signs of the observation group were pleural diffuse or localized thickening (92.5%) and mediastinal shift (20.00%) which were significantly higher than those in the control group (26.0%, 2.0%) (P<0.05). The enhancement of cancerous pleural effusion scanned by enhanced scan in the observation group was significantly better than that in the control group (P<0.05). The levels of pleural effusion CA199, CA153 and CEA in the observation group were significantly higher than those in the control group (P<0.05). The sensitivity and specificity of MSCT+CA199+CA153+CEA in the diagnosis of cancerous and tuberculous pleural effusion were significantly higher than those of MSCT, CEA and CA199+CA153 (P<0.05). Conclusion MSCT and tumor markers have certain value in the differential diagnosis of cancerous and tuberculous pleural effusion. The combined detection of the two can improve the diagnostic sensitivity and specificity.