The invention discloses a splicing method for tire mold images, which comprises the steps of inputting a set of photographed tire mold images, extracting the external boundary of the photographed tire mold images, fitting the external boundary to be arc-shaped, straightening the arc-shaped external boundary through the polar transformation process, conducting the pretreatment and the threshold segmentation, conducting the registration based on the gradient and phase-related method to obtain the overlapped part of two adjacent images, fusing by adopting a fusion method based on the combination of the optimal convergence and the weighted gradient fusion, splicing all adjacent images to form a first image based on the fusing result, determining the fore-and-aft overlapped part of the first image based on the registration algorithm, processing the first image in combination with the above fusion method to obtain a second image, and restoring the second image into the image of a circular tire mold through the polar coordinate inverse-transformation process. The method is good in splicing effect, simple, convenient and practical, which can be widely applied to the image processing field.