The co-cured joining method has several advantages over the adhesively bonded joining method because both the curing and the joining processes for the composite structures are achieved simultaneously. In this study, the tensile load-hearing capacities of co-cured double lap joints were investigated experimentally and compared with the analytical results calculated by finite element analysis. Co-cured double lap joint specimens with several bond parameters such as bond length, surface roughness, and stacking sequence of the composite laminate were fabricated and tested. From the experimental results, it was found that the failure mechanism of the co-cured double lap joint was cohesive failure by delamination at the first ply of the composite laminate in the co-cured double lap joint. Finally, optimum values of several bond parameters were determined. Analytical tensile load-bearing capacities of the co-cured double lap joints were calculated by the three-dimensional Tsai-Wu failure criterion using stress distributions obtained from finite element analysis.