Abstract: Objective To study the relationship between the lung function and chest image derived by spiral CT examination of pneumoconiosis patients,and to seek the best method to assess chronic lung injure degree. Methods The paired data of lung function parameters and chest spiral CT image of 91 pneumoconiosis cases were carefully analyzed. Results The main changes of chest spiral CT image were small opacity, aggregation of small opacity and large opacity diffusely scattered in the whole lung. The lung function examination showed that 75.82% patients had abnormality of lung function. The damages of lung function were mainly the restrictive and mixed ventilation dysfunction or diffusion dysfunction. The lung function parameters, such as VC,FVC,RV/TLC, FEV₁, FEV₁/FVC, MVV and DL_CO of patients with large opacity were different with those of the other patients(P<0.05). DL_CO of patients with aggregation of small opacity was different with that of patients with nodule in upper lobe or upper and middle lobe of the lungs (P<0.05). There was no internal relation between the lung function parameters and chest image characteristics, though it seemed there was higher abnormality of lung function among patients with more or bigger nodules. Conclusion The lung function examination and chest spiral CT image examination are independent methods in assessing lung injure degree of pneumoconiosis. The two methods altogether could contribute to observe the patients with pneumoconiosis and make the diagnosis accurately.