Abstract: Plasma exosomes (Pla-Exos) were extracted from rats by ultracentrifugation. The ultracentrifugation method extracted rat Pla-Exos at a speed of 150 000 ×g for 2.5 h. Various purification methods including ultracentrifugation, magnetic bead capture method, and ultrafiltration would be employed to purify Pla-Exos. The Pue-Exos were prepared via sonication-assisted and co-incubation methods. The influence factors and levels of the preparation of plasma exosomes carrying puerarin (Pue-Exos) were investigated by RSM plus CCD method with encapsulation rate as an index. Then the characterization, the stability, and in vitro release of Pue-Exos were determined. The particle sizes of exosomes purified by ultracentrifugation, ultrafiltration, or magnetic bead capture method were all within the range of 30-150 nm. The Western blot results showed that purified Pla-Exos and Pue-Exos contained marker proteins TSG101, CD63, and CD81. The TEM showed that purified Pla-Exos and Pue-Exos exhibited well-defined double-layered membrane vesicle structures. The optimal prescription conditions for preparing Pue-Exos were finally determined as follows: 1 h ultrasound time, 39 W ultrasound power, mass ratio of 10∶1. The prepared Pue-Exos exhibit good stability and sustained release, significantly enhancing the in vitro transpermeability of puerarin across the blood-brain barrier (P < 0.01). This study was approved by the Experimental Animal Ethics Review Committee of Hebei North University, and ethics approval number was HBNV202307012103.