Abstract: A novel interface structure was proposed to enhance the bonding strength at the interface of polycrystalline diamond (PDC) composite sheets, thereby improving their overall impact resistance and stability. The finite element method was employed to compare the stress distribution within composite sheets designed with the proposed interface structure against those with a conventional interface structure under external stress conditions. The study accounted for the influence of the structural parameters of the proposed interface structure, employing an optimal filling space method for sampling. The least square method was used to develop a second-order response surface approximation model of the structural field. Using the interface structure parameters as design variables, the maximum values of equivalent stress, maximum shear stress, and maximum principal stress in the structural field were set as design objectives, and a multi-objective genetic algorithm was then applied to optimize the response surface appro-ximation model. The results demonstrate that, under identical simulation conditions, the proposed interface structure reduces the maximum equivalent stress by 50.7%, the maximum shear stress by 52%, and the maximum principal stress by 22.4% compared to the conventional interface structure. For the optimized PDC composite sheet under the same conditions, equivalent stress, maximum shear stress, and maximum principal stress are all reduced by more than 14%. The optimized PDC composite sheet exhibited improved rock-breaking stability, effectively avoid stress concentration, and enhance thermal stability. The findings provide a theoretical basis for the optimization design of PDC composite sheets and introduce a novel optimization method that can help reduce research and development costs.