In this study, the optimized design for 130 liter storage fuel tank with 70MPa filling pressure has been investigated using a FEM technique and Taguchi design method. The strength safety of a composite fuel tank in which is fabricated by an aluminum liner of 6061-T6 material and carbon fiber wound composite layers of T800-24K has been analyzed based on the criterion of design safety of US DOT-CFFC and Korean Standard. The FEM computed results on the stress safety of 70MPa hydrogen gas tank were compared with a criterion of a stress ratio, 2.4 of US DOT-CFFC and Korean Standard, and indicated the safety. Thus, the optimized design elements based on the Taguchi's method were recommended as an aluminum liner thickness of 6.4mm, a carbon fiber laminate thickness in hoop direction of 31mm and a carbon fiber laminate thickness in helical direction of 10.2mm, which is represented by a design model of No. 5. 70MPa 130L . 6061-T6 T800-24K DOT-CFFC KS . 70MPa FEM , US DOT-CFFC KS 2.4 . , 5 , 6.4mm, 31mm, 10.2mm .