To investigate the computed tomography (CT) imaging and pathological basis of the linear shadows connecting pulmonary segmental arteries to horizontal fissure (hereinafter referred to as "linear shadow") on thin-slice CT.Collect 127 clinical cases to analyze the display and morphology of linear shadows on the thin-slice CT and to measure their length, thickness, and angle. Collect 11 autopsy specimens of coal worker's pneumoconiosis to conduct an imaging and pathology basis control study for the linear shadows.There is no correlation between the linear shadow and gender, age, and smoking history. Linear shadows are observed in 54.33% of patients. 93.33% of those linear shadows are straight lines. Generally, the lengths are less than 10 mm, the thicknesses are around 1 mm, and the scopes of angles are wide, range from acute angles to obtuse angles. The linear shadow is a banded structure consisting of loose connective tissue, small blood vessels, and small lymphatic vessels due to the visceral pleura recessed and fused into the lung.Linear shadows are intrinsic to the lung. The linear shadows consist of loose connective tissue, small blood vessels, and small lymphatic vessels.