As a critical component in vehicular passive safety systems, the automotive bumper beam significantly influences overall crash safety performance and lightweight potential. This study presents a comprehensive investigation into the lightweight design of a carbon fiber reinforced polymer (CFRP) bumper beam, systematically substituting a conventional aluminum alloy component based on the principle of equivalent bending stiffness. The research methodology integrates finite element modeling, design of experiments, and multi-objective decision-making to optimize crashworthiness. Initial design replaced the 3 mm aluminum beam with a 2.4 mm CFRP configuration using a [0°, 45°, 90°, -45°] ply sequence, demonstrating maintained structural integrity with substantial mass reduction potential. Through Latin Hypercube Sampling, 50 design configurations incorporating variations in panel thicknesses (five distinct sections) and ply orientation sequences were generated and evaluated under an 8 km/h frontal impact simulation. Crashworthiness was assessed through four key indicators: mass, specific energy absorption (SEA), maximum intrusion distance (Dm), and peak impact force (Fm). The entropy weight method objectively determined indicator weights, revealing maximum intrusion (49.27%) as the most critical factor, followed by mass (32.75%), peak force (9.75%), and SEA (8.23%). Subsequently, the Technique for Order Preference by Similarity to Ideal Solution (TOPSIS) was employed to comprehensively evaluate and rank all design alternatives. The optimized CFRP configuration (Scheme #38) achieved remarkable performance: 69.1% mass reduction (from 4.505 kg to 1.392 kg), 379.6% improvement in specific energy absorption, 12.6% reduction in peak impact force, while maintaining intrusion within acceptable design limits. This research establishes a robust framework for CFRP bumper beam optimization, successfully balancing lightweight objectives with enhanced crashworthiness, providing valuable insights for automotive lightweight safety component development.