Objective: To study the imaging performance and pulmonary function of pneumoconiosis patients at stage three. Methods: 89 cases of pneumoconiosis patients at stage three for high thousand volt back chest, chest CT, pulmonary function, analysis the relationship of high thousand volt back chest, chest CT manifestations and pulmonary function. Results: In patients with chest X-ray progressive massive fibrosis range of 2.31-102.95 cm², divide patients according to the X-ray performance into three groups, the difference of each group pulmonary function index FVC、FEV₁、PEF、MEF_75%、MEF_50%、MEF_25%、MVV is statistically significant (P<0.01) , the difference of FEV₁/FVC%、RV/TLC、DLCO is no statistical significance (P>0.05) . Checked by related, in pneumoconiosis patients at stage three, the X-ray manifestations and pulmonary function index FVC、FEV₁、FEV₁/FVC%、PEF、MEF_75%、MEF_50%、MEF_25%、MVV、DLCO showed a negative correlation (r=-0.326, -0.438, -0.251, -0.344, -0.317, -0.337, -0.425, -0.347, -0.230) . With the deterioration of the X-ray imaging findings, pulmonary function index FVC、FEV₁、FEV₁/FVC%、PEF、MEF_75%、MEF_50%、MEF_25%、MVV、DLCO is a trend of decrease (P<0.05) . The X-ray changes is not associated with RV/TLC. By linear regression analysis, FVC、FEV₁、FEV₁/FVC%、PEF、MEF_75%、MEF_50%、MEF_25%、MVV、DLCO regression equation are meaningful. The RV/TLC regression equations is meaningless. The volume of the patients with chest CT progressive massive fibrosis range of 4.86~179.74 cm³, divide patients according to the chest CT performance into three groups, the difference of each group pulmonary function index FVC、FEV₁、PEF、MEF_75%、MEF_50%、MEF_25%、MVV、RV/TLC is statistically (P<0.05) , the difference of FEV₁/FVC%、DLCO is no statistical significance (P>0.05) . Checked by related, in pneumoconiosis patients at stage three, chest CT manifestations and pulmonary function index FVC、FEV₁、FEV₁/FVC%、PEF、MEF_75%、MEF_50%、MEF_25%、MVV showed a negative correlation (r=-0.360, -0.419, -0.256, -0.432, -0.366, -0.326, -0.254, -0.405, ) , It is not associated with the RV/TLC、DLCO. With the deterioration of the chest CT imaging findings, pulmonary function index FVC、FEV₁、FEV₁/FVC%、PEF、MEF_75%、MEF_50%、MEF_25%、MVV is a trend of decrease (P<0.05) . By linear regression analysis, FVC、FEV₁、FEV₁/FVC%、PEF、MEF_75%、MEF_50%、MEF_25%、MVV regression equations are meaningful. The RV/TLC、DLCO regression equations are meaningless. Conclusion It is correlated with chest X-ray, chest CT manifestations and pulmonary function in pneumoconiosis patients at stage three, that could help guide clinicians comprehensive evaluation in patients with pulmonary function status.