Objective To explore a method for assessing the irregular small opacities profusion associated with occupational pneumoconiosis in chest computed tomography (CT). Methods A total of 20 occupational pneumoconiosis patients whose primary manifestation was irregular small opacities on chest digital radiography (DR) were collected as the research subjects using a retrospective study method. Comparative analysis was performed between chest DR and five mm coronal multi-planar reconstruction (MPR) of chest CT images to identify the causes of irregular small opacities. An evaluation method for the profusion of associated images of irregular small opacities in chest CT was established using technique for order preference by similarity to ideal solution-analytic hierarchy process (TOPSIS-AHP), and the results were compared against GBZ 70-2015 Diagnosis of Occupational Pneumoconiosis. Results The abnormal image distribution on the five mm coronal chest CT MPR images of the 20 patients was as follows: three cases of high-density small circular opacities, seven cases of low-density circular small opacities, six cases of diffuse low-density ground-glass opacities (GGO), four cases of reticular opacities, three cases of plate-like GGO, three cases of honeycomb opacities, and four cases of increasing lung texture. The CT values of abnormal images, from high to low were: honeycomb opacities > plate-like GGO > low-density circular small opacities > diffuse low-density GGO (all P<0.05). The consistency test results indicated that the evaluation method for the profusion of associated images of irregular small opacities in chest CT showed high level of agreement with the profusion determination criteria outlined in GBZ 70-2015 Diagnosis of Occupational Pneumoconiosis (Kappa=0.78). Conclusion Irregular small opacities observed on chest DR are formed by the superposition of multiple images of abnormal pulmonary fibrosis in patients with occupational pneumoconiosis. TOPSIS-AHP can be used to establish an evaluation method of the profusion of associated image of irregular small opacity in chest CT.