Abstract: The aim of this research is to optimize the preparation process of evening primrose oil-β-cyclodextrin inclusion complex.β-cyclodextrin inclusion of volatile oil from evening primrose oil was prepared by saturated aqueous solution method.Central composite design-response surface method was employed to optimize the preparation process, with the feed ratios, inclusion temperature and inclusion time as factors.Moreover, the comprehensive scores of inclusion rate and yield of inclusion complex were selected as the target. The inclusion complex of evening primrose oil was validated by infrared and differential scanning calorimetry method.The optimum preparation process was as follows: feed ratio 5∶ 1 ( β-cyclodextrin: evening primrose oil, g/m L) , the temperature was 55 ℃, and the time of inclusion was 1.8 h. Under the optimum conditions, the inclusion rate and the yield of the inclusion compound were 81.56% and 92.28% respectively.The result demonstrated that evening primrose oil and β-CD could form stable inclusion complexes.Additionally, the result of this experiment provided a theoretical basis for the application and development of the evening primrose oil.