Acute lung injury (ALI)/acute respiratory distress syndrome (ARDS) represents a spectrum of potentially fatal conditions that currently lack effective drug treatment. Recent researches suggest that Fibroblast Growth Factor 21 (FGF21) may protect against ALI/ARDS. However, the clinical use of FGF21 is limited by its rapid degradation, restricted targeting capabilities, and numerous adverse effects. Addressing this challenge, the study employs a pH-responsive nanoparticle delivery system known as Hexahistidine-metal Assembly (HmA) for administering FGF21. The entrapment efficiency (EE%) and loading capacity (LCwt%) of HmA exceed 90 % and 35 %, respectively, while the HmA@FGF21 nanoparticles exhibit an average size of 130 nm, a PDI value of approximately 0.28, and a zeta potential of 24 mV. In animal experiments, HmA@FGF21 administered in lipopolysaccharide (LPS)-induced lung injury significantly exceed those of standalone FGF21, including mitigating the pathological manifestations and reducing the wet/dry ratio, total protein concentration, and overall cell count in BALF of ALI, whether administered via the airway or intravenously. This therapeutic approach therefore shows promise for precise delivery of FGF21 to the lungs to treat ALI, and may offer a novel, and efficient method for delivery of potential pharmacological agents to address other lung diseases.