Abstract: Bovine serum albumin (BSA) was used as a carrier to encapsulate astaxanthin (AST) to prepare stable and controllable H/J-aggregates of astaxanthin/bovine serum albumin nanoparticles (H/J-ABNs) to improve the unstable and poorly water-dispersible properties of astaxanthin. In this study, stable and controlled H/J-aggregates of astaxanthin/bovine serum albumin nanoparticles (H/J-ABNs) were prepared using bovine serum albumin as a carrier at the condition of magnetic stirring speed 200 r/min for 20 min at 25 ℃, then the nanoparticles were characterized and preliminary binding mechanisms were explored. The results showed that the optimal conditions for the preparation of ABNs: H-ABNs were prepared by adding 20% volume fraction astaxanthin ethanol solution dropwise to 0.05 mg/mL BSA solution; other conditions were kept constant, and J-ABNs were prepared by adding 35% volume fraction astaxanthin ethanol solution to BSA solution; the physical and chemical properties showed that the particle sizes of H-ABNs and J-ABNs were (146±24) nm and (266±8) nm, zeta potentials were (-9.69±0.89) mV and(-6.16±0.45) mV, binding rates were 25.74% and 66.47%, and drug loading rates were 3.77% and 9.72%, respectively; the UV-vis spectra showed that the maximum absorption spectrum of H-ABNs was at 378 nm, while J-ABNs exhibited shoulder peaks near 520 nm and 560 nm; infrared spectroscopy analysis showed that the infrared characteristic absorption peaks of both BSA and astaxanthin in the aggregated astaxanthin nanoparticles were greatly weakened relative to the single protein and astaxanthin powder, indicating that the BSA conformation had changed in the presence of astaxanthin; fluorescence spectroscopy detection showed that the spectral absorption of H/J-ABNs was greatly weakened and blue-shifted, indicating that astaxanthin binding to BSA induced an increase in the hydrophobic microenvironment around the amino acid residues. Combined with various physicochemical characterizations and transmission electron microscopy analyses, it was confirmed that AST was successfully encapsulated in the hydrophobic microregion established by BSA as an aggregate, suggesting that bovine serum albumin has the potential to serve as a nano-delivery of aggregated astaxanthin.