Background: The aim of this study was to explore whether spectral computed tomography (CT) imaging parameters are associated with PD-L1 expression of lung adenocarcinoma. Methods: Spectral CT imaging parameters (iodine concentrations [IC] of lesion in arterial phase [ICLa] and venous phase [ICLv], normalized IC [NICa/NICv]normalized to the IC in the aorta, slope of the spectral HU curve [λHUa/λHUv] and enhanced monochromatic CT number [CT40keVa/v, CT70keVa/v] on 40 and 70 keV images) were analyzed in 34 prospectively enrolled lung adenocarcinoma patients with common molecular pathological markers including PD-L1 expression detected with immunohistochemistry. Patients were divided into two groups: positive PD-L1 expression and negative PD-L1 expression groups. Two-sample Mann-Whitney U test was used to test the difference of spectral CT imaging parameters between the two groups. Results: The CT40keVa (127.03 AE 37.92 vs. −54.69 AE 262.04), CT40keVv (124.39 AE 34.71 vs. −45.73 AE 238.97), CT70keVa (49.56 AE 11.76 vs. −136.51 AE 237.08) and CT70keVv (46.13 AE 15.81 vs. −133.10 AE 230.72) parameters in the positive PD-L1 expression group of lung adenocarcinoma were significantly higher than the negative PD-L1 expression group (all P < 0.05). There was no difference detected in IC, NIC and λHU of the arterial and venous phases between both groups (all P > 0.05). Conclusion: CT40keVa, CT40keVv, CT70keVa and CT70keVv were increased in positive PD-L1 expression. These parameters may be used to distinguish the PD-L1 expression state of lung adenocarcinoma.