With　increasing　concern　over　the　excessive　energy　consumption　and　environment　pollution,　structural　bionics　is　a　viable　new　tool　of　lightweight　design　by　mechanical　engineers.　The　structural　solutions　derived　from　nature　can　be　successfully　transferred　into　technical　construction　for　maximum　structural　efficiency　from　minimal　resources.　The　goal　of　the　study　is　to　develop　a　standard　methodology　for　bionic　mechanical　structures　with　dead-load　reduction　and　performance　improvement.　Similarity　theory　and　fuzzy　assessment　method　are　deployed　for　selection　of　analogical　samples　and　analysis　based　on　structure,　loading　and　function　similarities.　The　type　spectrum　of　lightweight　design　is　established　for　selection　convenience　and　principle　extraction,　vital　to　concept　designs.　Finite　element　method　is　used　as　an　effective　tool　for　mechanical　performance　simulation　and　comparison.　The　rapid　prototyping,　investment　casting　and　Numerical　Control　(NC)　machining　are　discussed　for　model　fabrication.　The　static　and　dynamic　test　results　indicate　that　the　bionic　models　are　lighter　but　stiffer　than　the　original　ones.　So　by　mimicking　biological　structural　principles,　the　structural　bionic　design　offers　a　new　solution　for　updating　traditional　design　concepts　and　achieving　maximum　structural　efficiency.