The work aims to propose a method for equivalent ladder cylinder unfolding of quasi-cylinder label image to solve the problem on whole surface unfolding of quasi-cylinder labels with unequal radii. Firstly, the minimum bounding rectangles of quasi-cylinder label of images from four perspectives were extracted. A pose estimation model was established according to the result extracted. Based on the quasi-cyl' idea of turning curve into straight, the equivalent ladder quasi -cylinder label 3D point cloud was established in combination with the label pose and outline from different perspectives. Finally, the method of bilinear interpolation was used to render the point cloud to get quasi-cylinder label unfolding results of unequal radii through image stitching with NCC algorithm. The quasi-cylindrical checkerboard label simulation models and the whole surface unfolding experiment of the chewing gum label showed that the proposed algorithm had higher accuracy than the traditional algorithms. For model 1, the variance in the x-axis and y-axis directions was 1.37 pixels and 0.58 pixels respectively. In conclusion, the equivalent ladder cylinder unfolding of quasi-cylinder label can effectively achieve whole surface unfolding of quasi-cylinder label, providing a good experimental basis for the subsequent label detection.