Objective To explore the ultrastructure characteristics of pulmonary arteries in smokers with normal lung function and with chronic obstructive pulmonary disease ( COPD) . Methods 33 patients who undertook surgery for peripheral lung cancer were collected. According to smoking history and pulmonary function, the patients were divided into three groups, ie. non-smokers with normal pulmonary function ( group A, n = 10) , smokers with normal pulmonary function ( group B, n = 13) , and smokers in stable phase of COPD ( group C, n = 10) . Normal lung tissues without cancer were sampled and observed under light and electric microscope. Results ①Compared with group A, the thickness of intimal layer of intra-acinar pulmonary muscular arteries of group B and C were significantly higher, the area of their lumenwas lower, and the proportion of their muscular arteries was higher( P lt; 0. 01) . ②Ultrastructure of small pulmonary arteries of group A showed that intimal layer was normal, so as to endothelial cells and smooth muscle cells. Collagen fiber was not increased. Ultrastructure observation of group B showed that endothelialcells were distorted, basal membrane was thick, and collagen fiber increased in vessels. Ultrastructure observation of group C showed that endothelial cells degenerated, vascular intima thickness increased, andsynthetic phenotype smooth muscle cells increased. ③ Smoking index was positively correlated with the proportion of muscular arteries and the proportion of intimal area( r =0. 464,0. 635, P lt;0. 05, respectively) ,and negatively correlated with the proportion of lumen area( r= - 0. 603, P lt;0. 05) . Conclusions Smokers with normal lung fuction and with COPD show the similar ultrastructural characterizations in endothelial cells, smooth muscle cells, and pulmonary arterial remodeling, which related closely to smoking.