The invention discloses a gradual stiffness damping design method for an underground structure. The design method includes the following steps: acquiring compressive strength values of the undergroundstructure and surrounding rock, and determining the strength difference between the underground structure and the surrounding rock according to the compressive strength values of the underground structure and the surrounding rock; arranging a gradual stiffness damping layer between the underground structure and the surrounding rock according to the strength difference between the underground structure and the surrounding rock. The gradual stiffness damping design method has the advantages that when seismic waves are transmitted to the provided gradient stiffness damping layer from the underground structure, the stiffness of the gradient stiffness damping layer is not uniform, and the seismic waves release a large quantity of energy during transmission in the gradient stiffness damping layer, so that impact of the seismic waves on the surrounding rock is reduced, and a good damping effect on the surrounding rock is achieved.