Polyurethane（PU）is an indispensable polymer material widely used in daily life. However，its flammability（limiting oxygen index LOI < 20%）and release of toxic smoke during combustion restrict its application in emerging fields such as smart wearables and robotic skins. Therefore，overcoming the limitations of traditional flame-retardant strategies has become an urgent issue in materials science. This review systematically summarizes key advances from 2021 to 2025，focusing on new flame-retardant paradigms based on biomimetic structural design and intelligent response mechanisms. Multiscale biomimicry includes macro-shape mimicry，such as sunflowers and cacti，and micro-structural mimicry，such as nacre-like layering and lotus-leaf superhydrophobic surfaces. This approach effectively balances flame retardancy with mechanical properties and introduces additional functions like oil-water separation，solar ice melting，and underwater antibacterial performance. Furthermore，this paper presents the concept of intelligent active protection. Integrating self-healing，fire early warning，and shape memory creates a synergistic system that forms a closed-loop protection mechanism covering sensing，alerting，and action. This advances flame-retardant technology from static，passive defense toward dynamic，adaptive response. Nevertheless，this field still faces three major challenges. First，environmental adaptability is limited，as most self-healing and shape memory behaviors require specific activation conditions. Second，complex biomimetic nanostructures are difficult to fabricate on a large scale at low cost. Third，the long-term cyclic stability and durability of coatings and composites need improvement. To address these challenges，future work should integrate artificial intelligence for material pre-design，combine animal and plant features to build multi-level defense systems，and develop biomass-based green closed-loop solutions across the material life cycle. These efforts will promote the development of biomimetic intelligent flame-retardant polyurethanes that can coexist sustainably with the environment.