Through integrating three designing factors, i.e., physical performance, environmental load, and economic cost, this study tentatively established a fuzzy-matrix theory based eco-design model for metal materials, and applied this model to the eco-design of three typical metal materials for automobile, i.e., steel, aluminum, and magnesium. The results show that, regarding the physical properties, steel is more advantageous than aluminum and magnesium towards the demand of automobile industry, and steel’s integrated indictor of physical-performance is 8.25% and 3.89% higher than those of aluminum and magnesium, respectively; with respect to the environmental load, aluminum is more advantageous than steel and magnesium, and the single score of life cycle assessment of aluminum is 10.68% and 22.59% lower than those of magnesium and steel, respectively; in general, integrating various designing factors, the eco-design implementation effect of aluminum is more conspicuous than those of steel and magnesium towards the application in automobile industry.