Recently, there has been a gradual increase in research on diaphragm functions fused with computer engineering-related techniques in the medical field. Therefore, this paper proposes a technique for evaluating the function of the diaphragm through chest computed tomography for chronic obstructive pulmonary disease (COPD) substitution. The proposed technique utilizes a patient’s chest segmentation algorithm to extract the diaphragm region from 2D slice images, and calculate the dynamic change experienced during breathing by calculating the diaphragm area and volume difference during inhalation and exhalation