The invention discloses a medical digital subtraction image fusion method based on ridgelet transformation, which comprises the following steps: (1) respectively performing ridgelet transformation on two images to obtain a ridgelet transformation matrix; (2) performing fusion processing; ( 3) Carry out ridgelet inverse transform to the ridgelet transformation matrix after fusion, and the reconstructed image obtained is the image after fusion; it is characterized in that: in step (1), the initial judgment threshold and the step size are set, and the process is carried out accordingly. Ridgelet transform, use the inverse transformation to reconstruct the fusion image, calculate the information entropy of the fusion image, use the dynamic fuzzy method to change the judgment threshold according to the step size and repeat the above operation, use the judgment threshold corresponding to the maximum information entropy as the final judgment threshold, and obtain the step (1 ) described ridgelet transformation matrix. The invention can effectively improve the information entropy of the fusion image, reduce the root mean square error rate, and the performance is better than other traditional fusion methods. The time complexity of the algorithm is low, and the results obtained are relatively accurate, which greatly enriches the texture details of medical images.