A new method is proposed in this paper for robust deign of configuration of multiple layers. The present design tool may enable the designers to estimate the flexural strength for the target combination of lamina. In line with these objectives, an experimental analysis was performed for 3 kinds of combinations of the number of orientation angles and 21 kinds of configurations of the symmetric 26 layers. The experimental results are compared with the theoretical considerations. From the viewpoint of robust design of configurations, the relation between flexural fracture strength and equivalent engineering modulus was also investigated. Finally, the procedure of practical robust design of composite laminate is also proposed.