Abstract: To improve the antioxidant properties and solubility of the almond protein-chlorogenic acid complex, this study employed the hydroxyl radical method to graft almond protein (AP) with chlorogenic acid (CA), forming the AP-CA conjugate. Techniques including Fourier transform infrared spectroscopy, ultraviolet absorption spectroscopy, fluorescence emission spectroscopy, X-ray diffraction, and scanning electron microscopy were used to physically characterize the complex. The results showed that the particle size of the AP-CA complex ranged from 390 to 425 nm, and the maximum loading capacity of CA in the complex reached 35.13 mg/100 mg. The solubility of the compound was reported to be 83.47%±2.15%, which was 1.11 times higher than that of AP. In addition, in the concentration range of 400~1000 μg/mL, the antioxidant activity of the AP-CA complex was significantly higher than that of the AP monomer (P<0.05). The enhancement effect of the AP-CA complex was positively correlated with the change in concentration gradient, exhibiting clear dose-dependent characteristics. Scanning electron microscopy showed that the surface morphology of CA and AP changed during the covalent bonding process, revealing more holes and more complex three-dimensional structures. Infrared, fluorescence, and ultraviolet spectroscopy analyses indicated that CA was successfully covalently bonded to AP. With the addition of CA, the fluorescence groups in AP were quenched, and the content of random coils in the secondary structure of AP increased (from 13.51% to 24.32%). The X-ray diffraction results showed that CA in the AP-CA complex exhibited an amorphous form, which was beneficial for a deeper understanding of the effect of the amorphous form of CA on water solubility and provided theoretical support for the optimization of AP-CA in the future. Meanwhile, the good solubility and antioxidant properties of AP-CA could enable its wider application in the fields of food processing, nutrition, and health industries.