Aiming at the detection problem of deformation on the inner surface of conical tubes in diversified application fields, a deformation detection method for conical tubes based on image analysis is proposed. The aim is to achieve quantitative analysis of deformation variables on the inner surface of conical tubes of 2 mm and above, and qualitative analysis of the circumferential direction of deformation. To this end, a complementary metal-oxide-semiconductor image-capturing module was first installed within a conical tube to acquire images of predefined circular-ring lines. Subsequently, these images were processed to detect the circular-ring lines using the smallest circumscribing circle, and an enhanced Canny edge detection algorithm was employed to extract edge details. Furthermore, feature data from the center of the ring lines were analyzed to ascertain deformation extents and locations. The analysis outcomes were then converted based on the relationship between the pixel space and spatial coordinates of the inner surface of the conical tube. Remarkably, this method facilitates high visualization and precise localization accuracies. Experimental results demonstrate that this method offers superior edge extraction, effective identification of deformations exceeding 2.05 mm with a relative error within 0.15 mm, and a localization precision of 0.01° for the deformations. These features satisfy the requisites for both qualitative and quantitative analyses of deformations within conical tubes across diverse application scenarios.