In this paper, parameters affecting the performance and durability of a one-sided composite patch for mixed-mode crack repairing is investigated, considering different thicknesses of the main plate. In different references, there is no unity of opinion on the effect of various parameters on the performance and durability of one-sided patches. In the present study, to eliminate this disagreement, 3D finite element method is employed. It is clear that the effect of each parameter strongly depends on the thickness of the repaired plate. Among the investigated parameters, the patch material, length and width of the patch, and adhesive thickness are more important and studied in this paper. Results reveal that the effect of different parameters on the performance and durability of one-sided patches depends not only on the thickness of the main plate but also on the patch material.