Abstract: Objective:To investigate the effects of extraction solvents on the biological activities of pomegranate seed oil(PSO)and the formation of its nanoemulsions. Methods:Five organic solvents were employed to extract PSO by ultrasound method. The extraction solvent was selected using principle composition analysis,on the basis of the oil yield,the contents of flavonoid,polyphenol,and punicic acid,antioxidant activity of PSO,turbidity and antibacterial activity of the nanoemulsions. The correlation of biological activities and the turbidity of nanoemulsions with the physicochemical constants of PSO were analyzed,respectively. Results:The extraction solvents had a great influence on the viscosity,acidity,content of active ingredients and biological activities of PSO. The antioxidant activity of PSO had obviously positive correlation with its saponification value and polyphenol content(P<0.05). The turbidity of nanoemulsions was negatively related with the saponification value of oil(r=-0.798).Ethyl acetate gained the highest integrated score in principle component analysis. Conclusion:The extraction solvents were evaluated based on the oil yield,active components,biological activities,and the formation of nanoemulsions of PSO. This assessment system would be helpful to develop advanced nano-preparations of PSO.