Ramie (Boehmeria nivea) is a kind of natural fiber that has good mechanical and environmental friendly properties. The fabric woven by ramie yarns shows excellent dimensional stability. Polypropylene (PP) was used as matrix for its recyclable and thermoplastic properties. PP is the widely used thermoplastics for composite and currently it is very common in building, construction, furniture and automotive products. Since the eco-power automobile body was designed for light-weight and low fuel consumption, there seems to be high potential application to automobile industry for ramie-PP composite. Therefore, in this paper, we developed a constitution of fabric to form stable structure reinforcement. The reinforcement and PP particles were treated in vulcanizer by thermo-compression technology. The fundamental mechanical properties of the composite were tested for finite element analysis (FEA). An eco-power automobile body was designed in Pro/E® Wildfire 5.0 and transferred to Finite Element Analysis Software for material and structural simulation analysis. Structural improvement and sizing optimization of the eco-power automobile body model were simulated to judge the material application and its structure effectiveness.